Rubber composition, and pneumatic tire

ABSTRACT

Provided are a rubber composition achieving balanced improvement in processability, fuel economy, rubber strength, abrasion resistance, wet-grip performance, and handling stability, and a pneumatic tire including the composition. The rubber composition includes, per 100% by mass of a rubber component, at least 35% by mass of SR, the composition including a conjugated diene polymer and a silica having N 2 SA of 40-400 m 2 /g, the polymer being obtained by polymerizing a monomer component including a conjugated diene compound and a silicon-containing vinyl compound using a polymerization initiator of formula (I): 
                         
to produce a copolymer, and reacting a compound containing nitrogen and/or silicon atoms with an active terminal of the copolymer, wherein the amount of the diene polymer is 1-90% by mass and the amount of polyisoprene-based rubber is 0-40% by mass, each per 100% by mass of the rubber component, and the amount of the silica is 10-150 parts by mass per 100 parts by mass of the rubber component.

TECHNICAL FIELD

The present invention relates to a rubber composition and a pneumatictire formed from the rubber composition.

BACKGROUND ART

With the recent increase in concern about environmental issues, thedemand on automobiles for better fuel economy is increasing. Better fueleconomy is also being required of rubber compositions used forautomotive tires. For example, rubber compositions containing aconjugated diene polymer (e.g., polybutadiene, butadiene-styrenecopolymer) and a filler (e.g., carbon black, silica) are used forautomotive tires.

Patent Literature 1 proposes an example of a method for improving thefuel economy; this method uses a diene rubber (modified rubber) that ismodified by an organosilicon compound containing an amino group and analkoxy group. Although the use of a modified rubber increases reactionefficiency between silica and rubber (polymer) to improve the fueleconomy, it tends to increase the Mooney viscosity so that theprocessability tends to deteriorate. Thus, good fuel economy and goodprocessability cannot be achieved simultaneously. Furthermore, the useof a modified rubber may lead to excessively tight bond between silicaand rubber so that the rubber strength and the abrasion resistance maydecrease.

Additionally, as rubber compositions for automobile tires need to beexcellent in wet-grip performance and handling stability in view ofsafety, a technique is desired which achieves balanced improvements inthese properties as well as fuel economy, processability, rubberstrength and abrasion resistance at high levels.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2000-344955 A

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to solve the problems identifiedabove by providing a rubber composition capable of achieves a balancedimprovement in processability, fuel economy, rubber strength, abrasionresistance, wet-grip performance, and handling stability, and byproviding a pneumatic tire formed from the rubber composition.

Solution to Problem

The present invention relates to a rubber composition, including, basedon 100% by mass of a rubber component, not less than 35% by mass ofstyrene-butadiene rubber, the rubber composition comprising

a conjugated diene polymer, and

a silica having a nitrogen adsorption specific surface area of 40 to 400m²/g,

the conjugated diene polymer being obtained by polymerizing a monomercomponent including a conjugated diene compound and a silicon-containingvinyl compound in the presence of a polymerization initiator representedby the following formula (I):

wherein i represents 0 or 1; R¹¹ represents a C₁₋₁₀₀ hydrocarbylenegroup; R¹² and R¹³ each represent an optionally substituted hydrocarbylgroup or a trihydrocarbylsilyl group, or R¹² and R¹³ are bonded to eachother to form a hydrocarbylene group optionally containing at least one,as a hetero atom, selected from the group consisting of a silicon atom,a nitrogen atom, and an oxygen atom; and M represents an alkali metalatom, to produce a copolymer, and

then reacting a compound containing at least one of a nitrogen atom anda silicon atom with an active terminal of the copolymer,

wherein an amount of the conjugated diene polymer is 1 to 90% by massand an amount of a polyisoprene-based rubber is 0 to 40% by mass, eachbased on 100% by mass of the rubber component, and

an amount of the silica is 10 to 150 parts by mass for each 100 parts bymass of the rubber component.

R¹¹ in the formula (I) is preferably a group represented by thefollowing formula (Ia):

wherein R¹⁴ represents a hydrocarbylene group including at least one ofa structural unit derived from a conjugated diene compound and astructural unit derived from an aromatic vinyl compound; and nrepresents an integer of 1 to 10.

R¹⁴ in the formula (Ia) is preferably a hydrocarbylene group includingfrom one to ten isoprene-derived structural unit(s).

The silicon-containing vinyl compound is preferably a compoundrepresented by the following formula (II):

wherein m represents 0 or 1; R²¹ represents a hydrocarbylene group; X¹,X², and X³ each represent a substituted amino group, a hydrocarbyloxygroup, or an optionally substituted hydrocarbyl group.

The conjugated diene polymer preferably contains a structural unitderived from an aromatic vinyl compound.

The silica preferably includes silica (1) having a nitrogen adsorptionspecific surface area of at least 50 m²/g but less than 120 m²/g, andsilica (2) having a nitrogen adsorption specific surface area of notless than 120 m²/g.

The rubber composition preferably includes a solid resin having a glasstransition temperature of 60 to 120° C. in an amount of 1 to 30 parts bymass for each 100 parts by mass of the rubber component.

Preferably, the silica includes silica (1) having a nitrogen adsorptionspecific surface area of at least 50 m²/g but less than 120 m²/g, andsilica (2) having a nitrogen adsorption specific surface area of notless than 120 m²/g, and the rubber composition includes a solid resinhaving a glass transition temperature of 60 to 120° C. in an amount of 1to 30 parts by mass for each 100 parts by mass of the rubber component.

The rubber composition preferably includes a mercapto group-containingsilane coupling agent in an amount of 0.5 to 20 parts by mass for each100 parts by mass of the silica.

Preferably, the rubber composition includes a mercapto group-containingsilane coupling agent in an amount of 0.5 to 20 parts by mass for each100 parts by mass of the silica, and the silica includes silica (1)having a nitrogen adsorption specific surface area of at least 50 m²/gbut less than 120 m²/g, and silica (2) having a nitrogen adsorptionspecific surface area of not less than 120 m²/g.

The rubber composition preferably includes a mercapto group-containingsilane coupling agent in an amount of 0.5 to 20 parts by mass for each100 parts by mass of the silica, and a solid resin having a glasstransition temperature of 60 to 120° C. in an amount of 1 to 30 parts bymass for each 100 parts by mass of the rubber component.

Preferably, the rubber composition includes a mercapto group-containingsilane coupling agent in an amount of 0.5 to 20 parts by mass for each100 parts by mass of the silica, the silica includes silica (1) having anitrogen adsorption specific surface area of at least 50 m²/g but lessthan 120 m²/g, and silica (2) having a nitrogen adsorption specificsurface area of not less than 120 m²/g, and the rubber compositionincludes a solid resin having a glass transition temperature of 60 to120° C. in an amount of 1 to 30 parts by mass for each 100 parts by massof the rubber component.

Preferably, the rubber composition includes a mercapto group-containingsilane coupling agent in an amount of 0.5 to 20 parts by mass for each100 parts by mass of the silica, and

the silane coupling agent is at least one of a compound represented bythe formula (1) below, and a compound containing a linking unit Arepresented by the formula (2) below and a linking unit B represented bythe formula (3) below,

wherein R¹⁰¹ to R¹⁰³ each represent a branched or unbranched C₁₋₁₂ alkylgroup, a branched or unbranched C₁₋₁₂ alkoxy group, or a grouprepresented by —O—(R¹¹¹—O)_(z)—R¹¹² where z R¹¹¹s each represent abranched or unbranched C₁₋₃₀ divalent hydrocarbon group, and z R¹¹¹s maybe the same as or different from one another; R¹¹² represents a branchedor unbranched C₁₋₃₀ alkyl group, a branched or unbranched C₂₋₃₀ alkenylgroup, a C₆₋₃₀ aryl group, or a C₇₋₃₀ aralkyl group; and z represents aninteger of 1 to 30, and R¹⁰¹ to R¹⁰³ may be the same as or differentfrom one another; and R¹⁰⁴ represents a branched or unbranched C₁₋₆alkylene group;

wherein R²⁰¹ represents a hydrogen atom, a halogen atom, a branched orunbranched C₁₋₃₀ alkyl group, a branched or unbranched C₂₋₃₀ alkenylgroup, a branched or unbranched C₂₋₃₀ alkynyl group, or the alkyl groupin which a terminal hydrogen atom is replaced with a hydroxyl group or acarboxyl group; R²⁰² represents a branched or unbranched C₁₋₃₀ alkylenegroup, a branched or unbranched C₂₋₃₀ alkenylene group, or a branched orunbranched C₂₋₃₀ alkynylene group; and R²⁰¹ and R²⁰² may be joinedtogether to form a cyclic structure.

Preferably, the silica includes silica (1) having a nitrogen adsorptionspecific surface area of at least 50 m²/g but less than 120 m²/g, andsilica (2) having a nitrogen adsorption specific surface area of notless than 120 m²/g, and

the nitrogen adsorption specific surface areas and amounts of the silica(1) and the silica (2) satisfy the following inequalities:(Nitrogen adsorption specific surface area of silica (2))/(Nitrogenadsorption specific surface area of silica (1))≧1.4, and(Amount of silica (1))×0.06≦(Amount of silica (2))≦(Amount of silica(1))×15.

Preferably, the rubber composition includes at least one of

at least one liquid resin having a glass transition temperature of −40to 20° C. selected from the group consisting of aromatic petroleumresins, terpene resins, and rosin resins, and

a plasticizer having a glass transition temperature of −40 to 20° C.,and

a combined amount of the liquid resin and the plasticizer is 1 to 30parts by mass for each 100 parts by mass of the rubber component.

The rubber composition preferably has a tan δ peak temperature of notlower than −16° C.

The rubber composition is preferably for use in a tread.

The present invention also relates to a pneumatic tire, formed from therubber composition.

Advantageous Effects of Invention

The rubber composition of the present invention is a rubber compositionincluding a specific amount of styrene-butadiene rubber together with aspecific amount of a specific conjugated diene polymer and a specificamount of a specific silica. Thus, the rubber composition enables toprovide a pneumatic tire that achieves a balanced improvement inprocessability, fuel economy, rubber strength, abrasion resistance,wet-grip performance, and handling stability (particularly, handlingstability on dry road surface).

DESCRIPTION OF EMBODIMENTS

As used herein, the hydrocarbyl group denotes a monovalent groupprovided by removing one hydrogen atom from a hydrocarbon; thehydrocarbylene group denotes a divalent group provided by removing twohydrogen atoms from a hydrocarbon; the hydrocarbyloxy group denotes amonovalent group provided by replacing the hydrogen atom of a hydroxylgroup with a hydrocarbyl group; the substituted amino group denotes agroup provided by replacing at least one hydrogen atom of an amino groupwith a monovalent atom other than a hydrogen atom or with a monovalentgroup, or denotes a group provided by replacing two hydrogen atoms of anamino group with a divalent group; the hydrocarbyl group having asubstituent (hereinafter, also referred to as substituted hydrocarbylgroup) denotes a monovalent group provided by replacing at least onehydrogen atom of a hydrocarbyl group with a substituent; and thehydrocarbylene group containing a hetero atom (hereinafter, alsoreferred to as hetero atom-containing hydrocarbylene group) denotes adivalent group provided by replacing a hydrogen atom and/or a carbonatom other than the carbon atoms from which a hydrogen atom has beenremoved in a hydrocarbylene group with a group containing a hetero atom(an atom other than carbon and hydrogen atoms).

The conjugated diene polymer according to the present invention isobtained by

polymerizing a monomer component including a conjugated diene compoundand a silicon-containing vinyl compound in the presence of apolymerization initiator represented by the following formula (I):

wherein i represents 0 or 1; R¹¹ represents a C₁₋₁₀₀ hydrocarbylenegroup; R¹² and R¹³ each represent an optionally substituted hydrocarbylgroup or a trihydrocarbylsilyl group, or R¹² and R¹³ are bonded to eachother to form a hydrocarbylene group optionally containing at least one,as a hetero atom, selected from the group consisting of a silicon atom,a nitrogen atom, and an oxygen atom; and M represents an alkali metalatom, to produce a copolymer, and

then reacting a compound containing a nitrogen atom and/or a siliconatom with an active terminal of the copolymer.

As used herein, the term “modifying” means bonding a copolymercontaining a diene compound, or a copolymer containing a diene compoundand an aromatic vinyl compound, to a compound other than thecompound(s). The above conjugated diene polymer has a structure in whicha polymerization initiation terminal is modified by the polymerizationinitiator represented by the formula (I); a main chain is modified bycopolymerization with a silicon-containing vinyl compound; and atermination terminal is modified by a compound containing a nitrogenatom and/or a silicon atom, a silicon-containing vinyl compound. Use ofthe conjugated diene polymer in combination with other rubbers (e.g.polyisoprene-based rubbers) enables to disperse silica well and achievea balanced improvement in fuel economy, rubber strength, abrasionresistance, wet-grip performance, and handling stability. In general,the use of a modified rubber in which all of an initiation terminal, amain chain and a termination terminal are modified tends to greatlydeteriorate the processability. In contrast, the use of the conjugateddiene polymer in which each of an initiation terminal, a main chain anda termination terminal is modified by a specific compound enables toensure good processability, and furthermore, enables to synergisticallyenhance the effects of improving the fuel economy, rubber strength,abrasion resistance, wet-grip performance, and handling stability. Thus,balanced improvements in processability, fuel economy, rubber strength,abrasion resistance, wet-grip performance, and handling stability can beachieved at high levels.

In the formula (I), i is 0 or 1, and preferably 1.

R¹¹ in the formula (I) is a C₁₋₁₀₀ hydrocarbylene group, preferably aC₆₋₁₀₀ hydrocarbylene group, and more preferably a C₇₋₈₀ hydrocarbylenegroup. If the R¹¹ has more than 100 carbon atoms, the polymerizationinitiator has an increased molecular weight, which may reduce the costefficiency and the handleability during the polymerization.

Plural kinds of compounds different in the carbon number of R¹¹ may beused in combination as the polymerization initiator represented by theformula (I).

R¹¹ in the formula (I) is preferably a group represented by thefollowing formula (Ia):

wherein R¹⁴ represents a hydrocarbylene group including at least one ofa structural unit derived from a conjugated diene compound and astructural unit derived from an aromatic vinyl compound; and nrepresents an integer of 1 to 10.

R¹⁴ in the formula (Ia) represents a hydrocarbylene group including atleast one of a structural unit derived from a conjugated diene compoundand a structural unit derived from an aromatic vinyl compound,preferably a hydrocarbylene group including an isoprene-derivedstructural unit, and more preferably a hydrocarbylene group includingfrom one to ten isoprene-derived structural unit(s).

The number of at least one of the structural unit derived from aconjugated diene compound and the structural unit derived from anaromatic vinyl compound in R¹⁴ is preferably from one to ten, and morepreferably from one to five.

In the formula (Ia), n represents an integer of 1 to 10, and preferablyan integer of 2 to 4.

Examples of R¹¹ include a group obtained by bonding from one to tenisoprene-derived structural unit(s) and a methylene group, a groupobtained by bonding from one to ten isoprene-derived structural unit(s)and an ethylene group, and a group obtained by bonding from one to tenisoprene-derived structural unit(s) and a trimethylene group; andpreferably a group obtained by bonding from one to ten isoprene-derivedstructural unit(s) and a trimethylene group.

In the formula (I), R¹² and R¹³ each are an optionally substitutedhydrocarbyl group or a trihydrocarbylsilyl group, or R¹² and R¹³ arebonded to each other to form a hydrocarbylene group optionallycontaining at least one, as a hetero atom, selected from the groupconsisting of a silicon atom, a nitrogen atom, and an oxygen atom.

The optionally substituted hydrocarbyl group is a hydrocarbyl group orsubstituted hydrocarbyl group. Examples of the substituent in thesubstituted hydrocarbyl group include a substituted amino group and ahydrocarbyloxy group. Examples of the hydrocarbyl group include acyclicalkyl groups such as a methyl group, an ethyl group, an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, a sec-butylgroup, a tert-butyl group, an n-pentyl group, an n-hexyl group, ann-octyl group, and an n-dodecyl group; cyclic alkyl groups such as acyclopentyl group and a cyclohexyl group; and aryl groups such as aphenyl group and a benzyl group, and preferably acyclic alkyl groups,and more preferably C₁₋₄ acyclic alkyl groups. Examples of thesubstituted hydrocarbyl group in which the substituent is a substitutedamino group include an N,N-dimethylaminomethyl group, a2-N,N-dimethylaminoethyl group, and a 3-N,N-dimethylaminopropyl group.Examples of the substituted hydrocarbyl group in which the substituentis a hydrocarbyloxy group include a methoxymethyl group, a methoxyethylgroup, and an ethoxymethyl group. Among the above examples, ahydrocarbyl group is preferable; a C₁₋₄ acyclic alkyl group is morepreferable; and a methyl group or an ethyl group is still morepreferable.

Examples of the trihydrocarbylsilyl group include a trimethylsilylgroup, and a tert-butyl-dimethylsilyl group. A trimethylsilyl group ispreferable.

The hydrocarbylene group optionally containing at least one, as a heteroatom, selected from the group consisting of a silicon atom, a nitrogenatom, and an oxygen atom is a hydrocarbylene group, or a heteroatom-containing hydrocarbylene group in which the hetero atom is atleast one selected from the group consisting of a silicon atom, anitrogen atom and an oxygen atom. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is at least one selectedfrom the group consisting of a silicon atom, a nitrogen atom and anoxygen atom include a hetero atom-containing hydrocarbylene group inwhich the hetero atom is a silicon atom, a hetero atom-containinghydrocarbylene group in which the hetero atom is a nitrogen atom, and ahetero atom-containing hydrocarbylene group in which the hetero atom isan oxygen atom. Examples of the hydrocarbylene group include alkylenegroups such as a tetramethylene group, a pentamethylene group, ahexamethylene group, a pent-2-ene-1,5-diyl group, and a2,2,4-trimethylhexane-1,6-diyl group; and alkenediyl groups such as apent-2-ene-1,5-diyl group, and preferably alkylene groups, and morepreferably C₄₋₇ alkylene groups. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is a silicon atom includea group represented by —Si(CH₃)₂—CH₂—CH₂—Si(CH₃)₂—. Examples of thehetero atom-containing hydrocarbylene group in which the hetero atom isa nitrogen atom include a group represented by —CH═N—CH═CH— and a grouprepresented by —CH═N—CH₂—CH₂—. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is an oxygen atom includea group represented by —CH₂—CH₂—O—CH₂—CH₂—. Among the above examples, ahydrocarbylene group is preferable; a C₄₋₇ alkylene group is morepreferable; and a tetramethylene group, a pentamethylene group, and ahexamethylene group are still more preferable.

Preferably, R¹² and R¹³ each are a hydrocarbyl group, or R¹² and R¹³ arebonded to each other to form a hydrocarbylene group. More preferably,R¹² and R¹³ each are a acyclic alkyl group, or R¹² and R¹³ are bonded toeach other to form a C₄₋₇ alkylene group. Still more preferably, R¹² andR¹³ each are a methyl group or an ethyl group.

M in the formula (I) represents an alkali metal atom. Examples of thealkali metal atom include Li, Na, K, and Cs; and a preferable examplethereof is Li.

The polymerization initiator represented by the formula (I) in which iis 1 may be a compound formed from one to five isoprene-derivedstructural unit(s) polymerized with an aminoalkyllithium compound.Examples of the aminoalkyllithium compound includeN,N-dialkylaminoalkyllithiums such as3-(N,N-dimethylamino)-1-propyllithium,3-(N,N-diethylamino)-1-propyllithium,3-(N,N-di-n-butylamino)-1-propyllithium,4-(N,N-dimethylamino)-1-butyllithium,4-(N,N-diethylamino)-1-butyllithium,4-(N,N-di-n-propylamino)-1-butyllithium, and3-(N,N-di-n-butylamino)-1-butyllithium; hetero atom-free cyclicaminoalkyllithium compounds such as 3-(1-pyrrolidino)-1-propyllithium,3-(1-piperidino)-1-propyllithium,3-(1-hexamethyleneimino)-1-propyllithium, and3-[1-(1,2,3,6-tetrahydropyridino)]-1-propyllithium; and heteroatom-containing cyclic aminoalkyllithium compounds such as3-(1-morpholino)-1-propyllithium, 3-(1-imidazolyl)-1-propyllithium,3-(4,5-dihydro-1-imidazolyl)-1-propyllithium, and3-(2,2,5,5-tetramethyl-1-aza-2,5-disila-1-cyclopentyl)-1-propyllithium,and preferably N,N-dialkylaminoalkyllithium, and more preferably3-(N,N-dimethylamino)-1-propyllithium or3-(N,N-diethylamino)-1-propyllithium.

Examples of the polymerization initiator represented by the formula (I)in which i is 0 include lithium hexamethyleneimide, lithium pyrrolidide,lithium piperidide, lithium heptamethyleneimide, lithiumdodecamethyleneimide, lithium dimethylamide, lithium diethylamide,lithium dipropylamide, lithium dibutylamide, lithium dihexylamide,lithium diheptylamide, lithium dioctylamide, lithiumdi-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperadide,lithium ethylpropylamide, lithium ethylbutylamide, lithiummethylbutylamide, lithium ethylbenzylamide, and lithiummethylphenethylamide.

The polymerization initiator represented by the formula (I) in which iis 0 may be prepared in advance from a secondary amine and ahydrocarbyllithium compound before it is used for the polymerizationreaction, or may be prepared in the polymerization system. Examples ofthe secondary amine include dimethylamine, diethylamine, dibutylamine,dioctylamine, dicyclohexylamine, and diisobutylamine. Other examplesthereof include cyclic amines, such as azacycloheptane (i.e.hexamethyleneimine), 2-(2-ethylhexyl)pyrrolidine,3-(2-propyl)pyrrolidine, 3,5-bis(2-ethylhexyl)piperidine,4-phenylpiperidine, 7-decyl-1-azacyclotridecane,3,3-dimethyl-1-azacyclotetradecane, 4-dodecyl-1-azacyclooctane,4-(2-phenylbutyl)-1-azacyclooctane,3-ethyl-5-cyclohexyl-1-azacycloheptane, 4-hexyl-1-azacycloheptane,9-isoamyl-1-azacycloheptadecane, 2-methyl-1-azacycloheptadec-9-ene,3-isobutyl-1-azacyclododecane, 2-methyl-7-t-butyl-1-azacyclododecane,5-nonyl-1-azacyclododecane,8-(4-methylphenyl)-5-pentyl-3-azabicyclo[5.4.0]undecane,1-butyl-6-azabicyclo[3.2.1]octane, 8-ethyl-3-azabicyclo[3.2.1]octane,1-propyl-3-azabicyclo[3.2.2]nonane,3-(t-butyl)-7-azabicyclo[4.3.0]nonane, and1,5,5-trimethyl-3-azabicyclo[4.4.0]decane.

The polymerization initiator represented by the formula (I) ispreferably a compound in which i is 1, more preferably a compound formedfrom one to five isoprene-derived structural unit(s) polymerized withN,N-aminoalkyllithium, and still more preferably a compound formed fromone to five isoprene-derived structural unit(s) polymerized with3-(N,N-dimethylamino)-1-propyllithium or3-(N,N-diethylamino)-1-propyllithium.

The amount of the polymerization initiator represented by the formula(1) to be used is preferably 0.01 to 15 mmol, and more preferably 0.1 to10 mmol, for each 100 g of the monomer component used in thepolymerization.

In the present invention, other polymerization initiators, such asn-butyllithium, may be used in combination, if necessary.

Examples of the conjugated diene compound include 1,3-butadiene,isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1,3-hexadiene, andmyrcene. Any of these may be used alone or two or more of these may beused in combination. In view of easy availability, the conjugated dienecompound is preferably 1,3-butadiene or isoprene.

The silicon-containing vinyl compound is preferably a compoundrepresented by the following formula (II):

wherein m represents 0 or 1; R²¹ represents a hydrocarbylene group; X¹,X², and X³ each represent a substituted amino group, a hydrocarbyloxygroup, or an optionally substituted hydrocarbyl group.

Here, m in the formula (II) is 0 or 1, and preferably 0.

Examples of the hydrocarbylene group in the formula (II) include analkylene group, an alkenediyl group, an arylene group, and a group inwhich an arylene group and an alkylene group are bonded. Examples of thealkylene group include a methylene group, an ethylene group, and atrimethylene group. Examples of the alkenediyl group include a vinylenegroup and an ethylene-1,1-diyl group. Examples of the arylene groupinclude a phenylene group, a naphthylene group, and a biphenylene group.Examples of the group in which an arylene group and an alkylene groupare bonded include a group in which a phenylene group and a methylenegroup are bonded, and a group in which a phenylene group and an ethylenegroup are bonded.

R²¹ is preferably an arylene group, and more preferably a phenylenegroup.

In the formula (II), X¹, X² and X³ each are a substituted amino group, ahydrocarbyloxy group, or an optionally substituted hydrocarbyl group.Preferably, at least one of X¹, X² and X³ is a substituted amino group.More preferably, two of X¹, X² and X³ are substituted amino groups.

In the formula (II), the substituted amino group is preferably a grouprepresented by the following formula (IIa):

wherein R²² and R²³ each represent an optionally substituted hydrocarbylgroup or a trihydrocarbylsilyl group, or R²² and R²³ are bonded to eachother to form a hydrocarbylene group optionally containing, as a heteroatom, a nitrogen atom and/or an oxygen atom.

The optionally substituted hydrocarbyl group in the formula (IIa) is ahydrocarbyl group or a substituted hydrocarbyl group. Examples of thesubstituted hydrocarbyl group include a substituted hydrocarbyl group inwhich the substituent is a hydrocarbyloxy group. Examples of thehydrocarbyl group include acyclic alkyl groups such as a methyl group,an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group,an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an n-hexyl group, and an n-octyl group; cyclic alkyl groups suchas a cyclopentyl group and a cyclohexyl group; and aryl groups such as aphenyl group, a benzyl group, and a naphthyl group. The hydrocarbylgroup is preferably a acyclic alkyl group, and more preferably a methylgroup or an ethyl group. Examples of the substituted hydrocarbyl groupin which the substituent is a hydrocarbyloxy group include alkoxyalkylgroups such as a methoxymethyl group, an ethoxymethyl group, and amethoxyethyl group; and aryloxyalkyl groups such as a phenoxymethylgroup.

Examples of the trihydrocarbylsilyl group in the formula (IIa) includetrialkylsilyl groups such as a trimethylsilyl group, a triethylsilylgroup, and a tert-butyldimethylsilyl group.

The hydrocarbylene group optionally containing, as a hetero atom, anitrogen atom and/or an oxygen atom in the formula (IIa) is ahydrocarbylene group, or a hetero atom-containing hydrocarbylene groupin which the hetero atom is a nitrogen atom and/or an oxygen atom.Examples of the hetero atom-containing hydrocarbylene group in which thehetero atom is a nitrogen atom and/or an oxygen atom include ahydrocarbylene group containing a nitrogen atom as a hetero atom, and ahydrocarbylene group containing an oxygen atom as a hetero atom.Examples of the hydrocarbylene group include alkylene groups such as atrimethylene group, a tetramethylene group, a pentamethylene group, ahexamethylene group, a heptamethylene group, an octamethylene group, adecamethylene group, a dodecamethylene group, and a2,2,4-trimethylhexane-1,6-diyl group; and alkenediyl groups such as apent-2-ene-1,5-diyl group. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is a nitrogen atom includea group represented by —CH═N—CH═CH— and a group represented by—CH═N—CH₂—CH₂—. Examples of the hetero atom-containing hydrocarbylenegroup in which the hetero atom is an oxygen atom include a grouprepresented by —CH₂—CH₂—O—CH₂—CH₂—.

Preferably, R²² and R²³ each are an alkyl group, or R²² and R²³ arebonded to each other to form an alkylene group. R²² and R²³ each aremore preferably an alkyl group, and still more preferably a methyl groupor an ethyl group.

Examples of the substituted amino group represented by the formula (IIa)in which R²² and R²³ each are a hydrocarbyl group include dialkylaminogroups such as a dimethylamino group, a diethylamino group, anethylmethylamino group, a di-n-propylamino group, a diisopropylaminogroup, a di-n-butylamino group, a diisobutylamino group, adi-sec-butylamino group, and a di-tert-butylamino group; and diarylaminogroups such as a diphenylamino group. Preferable examples thereofinclude dialkylamino groups, and more preferable examples thereofinclude dimethylamino groups, diethylamino groups, and di-n-butylaminogroups. Examples of the substituted amino group in which R²² and R²³each are a substituted hydrocarbyl group in which the substituent is ahydrocarbyloxy group include di(alkoxyalkyl)amino groups such as adi(methoxymethyl)amino group and a di(ethoxymethyl)amino group. Examplesof the substituted amino group in which R²² and R²³ each are atrihydrocarbylsilyl group include trialkylsilyl group-containing aminogroups such as a bis(trimethylsilyl)amino group, abis(tert-butyldimethylsilyl)amino group, and anN-trimethylsilyl-N-methylamino group.

Examples of the substituted amino group represented by the formula (IIa)in which R²² and R²³ are bonded to each other to form a hydrocarbylenegroup include 1-alkyleneimino groups such as a 1-trimethyleneiminogroup, a 1-pyrrolidino group, a 1-piperidino group, a1-hexamethyleneimino group, a 1-heptamethyleneimino group, a1-octamethyleneimino group, a 1-decamethyleneimino group, and a1-dodecamethyleneimino group. Examples of the substituted amino group inwhich R²² and R²³ are bonded to each other to form a hydrocarbylenegroup containing a nitrogen atom as a hetero atom include a 1-imidazolylgroup and a 4,5-dihydro-1-imidazolyl group. Examples of the substitutedamino group in which R²² and R²³ are bonded to each other to form ahydrocarbylene group containing an oxygen atom as a hetero atom includea morpholino group.

The substituted amino group represented by the formula (IIa) ispreferably a dialkylamino group or a 1-alkyleneimino group; morepreferably a dialkylamino group; and still more preferably adimethylamino group, a diethylamino group, or a di-n-butylamino group.

Examples of the hydrocarbyloxy group in the formula (II) include alkoxygroups such as a methoxy group, an ethoxy group, an n-propoxy group, anisopropoxy group, an n-butoxy group, a sec-butoxy group, and atert-butoxy group; and aryloxy groups such as a phenoxy group and abenzyloxy group.

The optionally substituted hydrocarbyl group in the formula (II) is ahydrocarbyl group or a substituted hydrocarbyl group. Examples of thesubstituted hydrocarbyl group include a substituted hydrocarbyl group inwhich the substituent is a hydrocarbyloxy group. Examples of thehydrocarbyl group include alkyl groups such as a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, an n-butyl group, asec-butyl group, and a tert-butyl group; and aryl groups such as aphenyl group, a 4-methyl-1-phenyl group, and a benzyl group. Examples ofthe substituted hydrocarbyl group in which the substituent is ahydrocarbyloxy group include alkoxyalkyl groups such as a methoxymethylgroup, an ethoxymethyl group, and an ethoxyethyl group.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which one of X¹, X², and X³ is a substituted aminogroup, and m is 0 include (dialkylamino)dialkylvinylsilanes such as(dimethylamino)dimethylvinylsilane,(ethylmethylamino)dimethylvinylsilane,(di-n-propylamino)dimethylvinylsilane,(diisopropylamino)dimethylvinylsilane,(dimethylamino)diethylvinylsilane, (ethylmethylamino)diethylvinylsilane,(di-n-propylamino) diethylvinylsilane, and(diisopropylamino)diethylvinylsilane;[bis(trialkylsilyl)amino]dialkylvinylsilanes such as[bis(trimethylsilyl)amino]dimethylvinylsilane,[bis(t-butyldimethylsilyl)amino]dimethylvinylsilane,[bis(trimethylsilyl)amino]diethylvinylsilane, and[bis(t-butyldimethylsilyl)amino]diethylvinylsilane;(dialkylamino)di(alkoxyalkyl)vinylsilanes such as(dimethylamino)di(methoxymethyl)vinylsilane,(dimethylamino)di(methoxyethyl)vinylsilane,(dimethylamino)di(ethoxymethyl)vinylsilane,(dimethylamino)di(ethoxyethyl)vinylsilane,(diethylamino)di(methoxymethyl)vinylsilane,(diethylamino)di(methoxyethyl)vinylsilane,(diethylamino)di(ethoxymethyl)vinylsilane, and(diethylamino)di(ethoxyethyl)vinylsilane; and cyclicaminodialkylvinylsilane compounds such aspyrrolidinodimethylvinylsilane, piperidinodimethylvinylsilane,hexamethyleneiminodimethylvinylsilane,4,5-dihydro-imidazolyldimethylvinylsilane, andmorpholinodimethylvinylsilane.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which one of X¹, X², and X³ is a substituted aminogroup, and m is 1 include (dialkylamino)dialkylvinylphenylsilanes suchas (dimethylamino)dimethyl-4-vinylphenylsilane,(dimethylamino)dimethyl-3-vinylphenylsilane,(diethylamino)dimethyl-4-vinylphenylsilane,(diethylamino)dimethyl-3-vinylphenylsilane,(di-n-propylamino)dimethyl-4-vinylphenylsilane,(di-n-propylamino)dimethyl-3-vinylphenylsilane,(di-n-butylamino)dimethyl-4-vinylphenylsilane,(di-n-butylamino)dimethyl-3-vinylphenylsilane,(dimethylamino)diethyl-4-vinylphenylsilane,(dimethylamino)diethyl-3-vinylphenylsilane,(diethylamino)diethyl-4-vinylphenylsilane,(diethylamino)diethyl-3-vinylphenylsilane,(di-n-propylamino)diethyl-4-vinylphenylsilane,(di-n-propylamino)diethyl-3-vinylphenylsilane,(di-n-butylamino)diethyl-4-vinylphenylsilane, and(di-n-butylamino)diethyl-3-vinylphenylsilane.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which two of X¹, X², and X³ each are a substituted aminogroup, and m is 0 include bis(dialkylamino)alkylvinylsilanes such asbis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane,bis(di-n-propylamino)methylvinylsilane,bis(di-n-butylamino)methylvinylsilane,bis(dimethylamino)ethylvinylsilane, bis(diethylamino)ethylvinylsilane,bis(di-n-propylamino)ethylvinylsilane, andbis(di-n-butylamino)ethylvinylsilane;bis[bis(trialkylsilyl)amino]alkylvinylsilanes such asbis[bis(trimethylsilyl)amino]methylvinylsilane,bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane,bis[bis(trimethylsilyl)amino]ethylvinylsilane, andbis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane;bis(dialkylamino)alkoxyalkylsilanes such asbis(dimethylamino)methoxymethylvinylsilane,bis(dimethylamino)methoxyethylvinylsilane,bis(dimethylamino)ethoxymethylvinylsilane,bis(dimethylamino)ethoxyethylvinylsilane,bis(diethylamino)methoxymethylvinylsilane,bis(diethylamino)methoxyethylvinylsilane,bis(diethylamino)ethoxymethylvinylsilane, andbis(dimethylamino)ethoxyethylvinylsilane; and bis(cyclicamino)alkylvinylsilane compounds such asbis(pyrrolidino)methylvinylsilane, bis(piperidino)methylvinylsilane,bis(hexamethyleneimino)methylvinylsilane,bis(4,5-dihydroimidazolyl)methylvinylsilane, andbis(morpholino)methylvinylsilane.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which two of X¹, X², and X³ each are a substituted aminogroup, and m is 1 include bis(dialkylamino)alkylvinylphenylsilanes suchas bis(dimethylamino)methyl-4-vinylphenylsilane,bis(dimethylamino)methyl-3-vinylphenylsilane,bis(diethylamino)methyl-4-vinylphenylsilane,bis(diethylamino)methyl-3-vinylphenylsilane,bis(di-n-propylamino)methyl-4-vinylphenylsilane,bis(di-n-propylamino)methyl-3-vinylphenylsilane,bis(di-n-butylamino)methyl-4-vinylphenylsilane,bis(di-n-butylamino)methyl-3-vinylphenylsilane,bis(dimethylamino)ethyl-4-vinylphenylsilane,bis(dimethylamino)ethyl-3-vinylphenylsilane,bis(diethylamino)ethyl-4-vinylphenylsilane,bis(diethylamino)ethyl-3-vinylphenylsilane,bis(di-n-propylamino)ethyl-4-vinylphenylsilane,bis(di-n-propylamino)ethyl-3-vinylphenylsilane,bis(di-n-butylamino)ethyl-4-vinylphenylsilane, andbis(di-n-butylamino)ethyl-3-vinylphenylsilane.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which three of X¹, X², and X³ each are a substitutedamino group, and m is 0 include tris(dialkylamino)vinylsilanes such astris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane,tris(di-n-propylamino)vinylsilane, and tris(di-n-butylamino)vinylsilane.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which three of X¹, X², and X³ each are a substitutedamino group, and m is 1 include tris(dialkylamino)vinylphenylsilanessuch as tris(dimethylamino)-4-vinylphenylsilane,tris(dimethylamino)-3-vinylphenylsilane,tris(diethylamino)-4-vinylphenylsilane,tris(diethylamino)-3-vinylphenylsilane,tris(di-n-propylamino)-4-vinylphenylsilane,tris(di-n-propylamino)-3-vinylphenylsilane,tris(di-n-butylamino)-4-vinylphenylsilane, andtris(di-n-butylamino)-3-vinylphenylsilane.

Examples of the silicon-containing vinyl compound represented by theformula (II) in which X¹, X², and X³ are not a substituted amino group,and m is 0 include trialkoxyvinylsilanes such as trimethoxyvinylsilane,triethoxyvinylsilane, and tripropoxyvinylsilane;dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane andmethyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such asdi(tert-pentoxy)phenylvinylsilane and di(tert-butoxy)phenylvinylsilane;monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane;monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane andtert-pentoxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such astert-butoxymethylphenylvinylsilane andtert-butoxyethylphenylvinylsilane; and substituted alkoxyvinylsilanecompounds such as tris(β-methoxyethoxy)vinylsilane.

Moreover, examples of the silicon-containing vinyl compound includebis(trialkylsilyl)-aminostyrenes such as4-N,N-bis(trimethylsilyl)aminostyrene and3-N,N-bis(trimethylsilyl)aminostyrene; andbis(trialkylsilyl)aminoalkylstyrenes such as4-bis(trimethylsilyl)aminomethylstyrene,3-bis(trimethylsilyl)aminomethylstyrene,4-bis(trimethylsilyl)aminoethylstyrene, and3-bis(trimethylsilyl)aminoethylstyrene.

The silicon-containing vinyl compound is preferably a compoundrepresented by the formula (II), more preferably a compound representedby the formula (II) in which m is 0, and still more preferably acompound represented by the formula (II) in which two of X¹, X² and X³are dialkyl amino groups.

The silicon-containing vinyl compound is particularly preferablybis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane,or bis(di-n-butylamino) methylvinylsilane.

The amount of the silicon-containing vinyl compound used in productionof the conjugated diene polymer is preferably not less than 0.01% bymass, more preferably not less than 0.02% by mass, and still morepreferably not less than 0.05% by mass based on 100% by mass of thetotal amount of the monomer component used in the polymerization forachieving a balanced enhancement in processability, fuel economy, rubberstrength, abrasion resistance, wet-grip performance, and handlingstability. The amount is preferably not more than 20% by mass, morepreferably not more than 2% by mass, and still more preferably not morethan 1% by mass for achieving better cost efficiency and higher rubberstrength.

In the production of the conjugated diene polymer, the monomer componentmay further include polymerizable monomers in addition to the conjugateddiene compound and silicon-containing vinyl compound. The monomers maybe, for example, aromatic vinyl compounds, vinyl nitriles, andunsaturated carboxylic acid esters. Examples of the aromatic vinylcompounds include styrene, α-methylstyrene, vinyltoluene,vinylnaphthalene, divinylbenzene, trivinylbenzene, anddivinylnaphthalene. Examples of the vinyl nitriles includeacrylonitrile. Examples of the unsaturated carboxylic acid estersinclude methyl acrylate, ethyl acrylate, methyl methacrylate, and ethylmethacrylate. Aromatic vinyl compounds are preferable, and styrene ismore preferable among the above examples.

In the case where an aromatic vinyl compound is used in the productionof the conjugated diene polymer, the amount of the aromatic vinylcompound based on 100% by mass of the combined amount of the conjugateddiene compound and the aromatic vinyl compound is preferably not lessthan 10% by mass (the amount of the conjugated diene compound is notmore than 90% by mass), and more preferably not less than 15% by mass(the amount of the conjugated diene compound is not more than 85% bymass). Moreover, from a viewpoint of fuel economy, the amount of thearomatic vinyl compound is preferably not more than 50% by mass (theamount of the conjugated diene compound is not less than 50% by mass),and more preferably not more than 45% by mass (the amount of theconjugated diene compound is not less than 55% by mass).

In the production of the conjugated diene polymer, polymerization ispreferably performed in a hydrocarbon solvent that does not inactivatethe polymerization initiator represented by the formula (I). Examples ofthe hydrocarbon solvent include aliphatic hydrocarbons, aromatichydrocarbons, and alicyclic hydrocarbons. Examples of the aliphatichydrocarbons include propane, n-butane, iso-butane, n-pentane,iso-pentane, n-hexane, n-heptane, and n-octane. Examples of the aromatichydrocarbons include benzene, toluene, xylene, and ethylbenzene.Examples of the alicyclic hydrocarbons include cyclopentane andcyclohexane. The hydrocarbon solvent may be a mixture of variouscomponents, such as industrial hexane. It is preferably a C₂₋₁₂hydrocarbon.

The polymerization reaction may be performed in the presence of an agentfor adjusting the vinyl bond content in a conjugated diene unit, or anagent for adjusting distribution of a conjugated diene unit and amonomer unit based on a monomer other than conjugated diene in aconjugated diene-based polymer chain (hereinafter, collectively referredto as “adjusting agent”). Examples of the agents include ethercompounds, tertiary amine compounds, and phosphine compounds. Examplesof the ether compounds include cyclic ethers such as tetrahydrofuran,tetrahydropyran, and 1,4-dioxane; aliphatic monoethers such as diethylether and dibutyl ether; aliphatic diethers such as ethylene glycoldimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutylether, diethylene glycol diethyl ether, and diethylene glycol dibutylether; and aromatic ethers such as diphenyl ether and anisole. Examplesof the tertiary amine compounds include triethylamine, tripropylamine,tributylamine, N,N,N′,N′-tetramethylethylenediamine, N,N-diethylaniline,pyridine, and quinoline. Examples of the phosphine compounds includetrimethylphosphine, triethylphosphine, and triphenylphosphine. One ormore of them are used.

In the production of the conjugated diene polymer, the polymerizationinitiator may be supplied to a polymerization reactor before the monomercomponent is supplied to the polymerization reactor; or thepolymerization initiator may be supplied to the polymerization reactorafter the whole amount of the monomer component used in polymerizationis supplied to the polymerization reactor; or the polymerizationinitiator may be supplied to the polymerization reactor after a part ofthe monomer component used in polymerization is supplied to thepolymerization reactor. The polymerization initiator may be supplied atonce or continuously to the polymerization reactor.

In the production of the conjugated diene polymer, the monomer componentmay be supplied at once, continuously, or intermittently to thepolymerization reactor. Moreover, respective monomers may be suppliedseparately, or simultaneously to the polymerization reactor.

In the production of the conjugated diene polymer, the polymerizationtemperature is usually 25 to 100° C., preferably 35 to 90° C., and morepreferably 50 to 80° C. The polymerization time is usually 10 minutes to5 hours.

The conjugated diene polymer is obtained by polymerizing a monomercomponent including a conjugated diene compound and a silicon-containingvinyl compound in the presence of a polymerization initiator representedby the formula (I) to produce a copolymer, and then reacting a compoundcontaining a nitrogen atom and/or a silicon atom with an active terminalof the copolymer (the active terminal of the copolymer is considered tohave an alkali metal derived from the polymerization initiator)(terminal modification reaction). Specifically, the conjugated dienepolymer is obtained by adding a compound containing a nitrogen atomand/or a silicon atom to a polymerization solution and then mixing them.The amount of the compound containing a nitrogen atom and/or a siliconatom to be added to the polymerization solution is usually 0.1 to 3 mol,preferably 0.5 to 2 mol, and more preferably 0.7 to 1.5 mol, per mol ofan alkali metal derived from the polymerization initiator represented bythe formula (I).

The terminal modification reaction is performed usually at a temperaturefrom 25 to 100° C., preferably from 35 to 90° C., and more preferablyfrom 50 to 80° C. The time period for the reaction is usually 60 secondsto 5 hours, preferably 5 minutes to 1 hour, and more preferably 15minutes to 1 hour.

Preferable examples of the compound containing a nitrogen atom and/or asilicon atom include a compound containing a nitrogen atom and acarbonyl group.

The compound containing a nitrogen atom and a carbonyl group ispreferably a compound represented by the following formula (III):

wherein R³¹ represents an optionally substituted hydrocarbyl group, oris bonded with R³² to form a hydrocarbylene group optionally containing,as a hetero atom, a nitrogen atom and/or an oxygen atom, or is bondedwith R³⁴ to form a divalent group; R³² represents an optionallysubstituted hydrocarbyl group, or is bonded with R³¹ to form ahydrocarbylene group optionally containing, as a hetero atom, a nitrogenatom and/or an oxygen atom; and R³⁴ represents an optionally substitutedhydrocarbyl group, or a hydrogen atom, or is bonded with Rn to form adivalent group; R³³ represents a divalent group; and k represents 0 or1.

In the formula (III), the optionally substituted hydrocarbyl group inR³¹, R³² or R³⁴ is a hydrocarbyl group or a substituted hydrocarbylgroup. Examples of the substituted hydrocarbyl group include asubstituted hydrocarbyl group in which the substituent is ahydrocarbyloxy group, and a substituted hydrocarbyl group in which thesubstituent is a substituted amino group. Examples of the hydrocarbylgroup include alkyl groups such as a methyl group, an ethyl group, ann-propyl group, an isopropyl group, and an n-butyl group; alkenyl groupssuch as a vinyl group, an allyl group, and an isopropenyl group; andaryl groups such as a phenyl group. Examples of the substitutedhydrocarbyl group in which the substituent is a hydrocarbyloxy groupinclude alkoxyalkyl groups such as a methoxymethyl group, anethoxymethyl group, and an ethoxyethyl group. Examples of thesubstituted hydrocarbyl group in which the substituent is a substitutedamino group include (N,N-dialkylamino)alkyl groups such as a2-(N,N-dimethylamino) ethyl group, a 2-(N,N-diethylamino)ethyl group, a3-(N,N-dimethylamino)propyl group, and a 3-(N,N-diethylamino)propylgroup; (N,N-dialkylamino)aryl groups such as a4-(N,N-dimethylamino)phenyl group, a 3-(N,N-dimethylamino)phenyl group,a 4-(N,N-diethylamino)phenyl group, and a 3-(N,N-diethylamino)phenylgroup; (N,N-dialkylamino)alkylaryl groups such as a4-(N,N-dimethylamino)methylphenyl group and a4-(N,N-dimethylamino)ethylphenyl group; cyclic amino group-containingalkyl groups such as a 3-pyrrolidinopropyl group, a 3-piperidinopropylgroup, and a 3-imidazolylpropyl group; cyclic amino group-containingaryl groups such as a 4-pyrrolidinophenyl group, a 4-piperidinophenylgroup, and a 4-imidazolylphenyl group; and cyclic amino group-containingalkylaryl groups such as a 4-pyrrolidinoethylphenyl group, a4-piperidinoethylphenyl group, and a 4-imidazolylethylphenyl group.

In the formula (III), the hydrocarbylene group optionally containing, asa hetero atom, a nitrogen atom and/or an oxygen atom, formed by bondingof R³¹ and R³², is a hydrocarbylene group or a hetero atom-containinghydrocarbylene group in which the hetero atom is a nitrogen atom and/oran oxygen atom. Examples of the hetero atom-containing hydrocarbylenegroup in which the hetero atom is a nitrogen atom and/or an oxygen atominclude a hetero atom-containing hydrocarbylene group in which thehetero atom is a nitrogen atom and a hetero atom-containinghydrocarbylene group in which the hetero atom is an oxygen atom.Examples of the hydrocarbylene group include alkylene groups such as atrimethylene group, a tetramethylene group, a pentamethylene group, ahexamethylene group, a pentan-2-en-1,5-diyl group, and a2,2,4-trimethylhexane-1,6-diyl group; and arylene groups such as a1,4-phenylene group. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is a nitrogen atom includea group represented by —CH═N—CH═CH— and a group represented by—CH═N—CH₂—CH₂—. Examples of the hetero atom-containing hydrocarbylenegroup in which the hetero atom is an oxygen atom include a grouprepresented by —(CH₂)_(s)—O—(CH₂)_(t)— (s and t each are an integer of 1or more).

In the formula (III), examples of the divalent group formed by bondingof R³¹ and R³⁴, and the divalent group of R³³ include a hydrocarbylenegroup, a hetero atom-containing hydrocarbylene group in which the heteroatom is a nitrogen atom, a hetero atom-containing hydrocarbylene groupin which the hetero atom is an oxygen atom, a group in which ahydrocarbylene group and an oxygen atom are bonded, and a group in whicha hydrocarbylene group and a group represented by —NR³⁵— (R³⁵ representsa hydrocarbyl group or a hydrogen atom) are bonded. Examples of thehydrocarbylene group include alkylene groups such as a trimethylenegroup, a tetramethylene group, a pentamethylene group, a hexamethylenegroup, a pentan-2-en-1,5-diyl group, and a2,2,4-trimethylhexane-1,6-diyl group; and arylene groups such as a1,4-phenylene group. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is a nitrogen atom includea group represented by —CH═N—CH═CH— and a group represented by—CH═N—CH₂—CH₂—. Examples of the hetero atom-containing hydrocarbylenegroup in which the hetero atom is an oxygen atom include a grouprepresented by —(CH₂)_(s)—O—(CH₂)_(t)— (s and t each are an integer of 1or more). Examples of the group in which a hydrocarbylene group and anoxygen atom are bonded include a group represented by —(CH₂)_(r)—O— (rrepresents an integer of 1 or more). Examples of the group in which ahydrocarbylene group and a group represented by —NR³⁵— (R³⁵ represents ahydrocarbyl group or a hydrogen atom) are bonded include a grouprepresented by —(CH₂)_(p)—NR³⁵— (R³⁵ represents a hydrocarbyl group(preferably a C₁₋₆ hydrocarbyl group), or a hydrogen atom; and prepresents an integer of 1 or more).

Preferable examples of a compound represented by the formula (III)include a compound represented by the formula (III) in which k is 0, andR³⁴ is an optionally substituted hydrocarbyl group or a hydrogen atom,represented by the following formula (IIIa):

wherein, R³¹ represents an optionally substituted hydrocarbyl group, oris bonded with R³² to form a hydrocarbylene group optionally containing,as a hetero atom, a nitrogen atom and/or an oxygen atom; R³² representsan optionally substituted hydrocarbyl group, or is bonded with R³¹ toform a hydrocarbylene group optionally containing, as a hetero atom, anitrogen atom and/or an oxygen atom; and R³⁴ represents an optionallysubstituted hydrocarbyl group or a hydrogen atom.

In the formula (IIIa), description and examples of the optionallysubstituted hydrocarbyl group for R³¹, R³² or R³⁴, and thehydrocarbylene group optionally containing, as a hetero atom, a nitrogenatom and/or an oxygen atom, formed by bonding of R³¹ and R³², are thesame as those stated in the description of the formula (III).

In the formula (IIIa), R³¹ is preferably a C₁₋₁₀ hydrocarbyl group, oris bonded with R³² to form a C₃₋₁₀ hydrocarbylene group or a heteroatom-containing C₃₋₁₀ hydrocarbylene group in which the hetero atom is anitrogen atom. R³¹ is more preferably a C₁₋₁₀ alkyl group or a C₆₋₁₀aryl group, or is bonded with R³² to form a C₃₋₁₀ alkylene group, agroup represented by —CH═N—CH═CH—, or a group represented by—CH═N—CH₂—CH₂—. R³¹ is still more preferably a C₁₋₆ alkyl group, andparticularly preferably a methyl group or an ethyl group.

In the formula (IIIa), R³² is preferably a C₁₋₁₀ hydrocarbyl group, oris bonded with R³¹ to form a C₃₋₁₀ hydrocarbylene group or a heteroatom-containing C₃₋₁₀ hydrocarbylene group in which the hetero atom is anitrogen atom. R³² is more preferably a C₁₋₁₀ alkyl group or a C₆₋₁₀aryl group, or is bonded with R³¹ to form a C₃₋₁₀ alkylene group, agroup represented by —CH═N—CH═CH—, or a group represented by—CH═N—CH₂—CH₂—. R³² is still more preferably a C₁₋₆ alkyl group, andparticularly preferably a methyl group or an ethyl group.

In the formula (IIIa), R³⁴ is preferably a hydrocarbyl group or ahydrogen atom, more preferably a C₁₋₁₀ hydrocarbyl group or a hydrogenatom, still more preferably a C₁₋₆ alkyl group or a hydrogen atom, andparticularly preferably a hydrogen atom, a methyl group or an ethylgroup.

Examples of the compound represented by the formula (IIIa) in which R³⁴is a hydrocarbyl group include N,N-dihydrocarbylacetamides such asN,N-dimethylacetamide, N,N-diethylacetamide, andN-methyl-N-ethylacetamide; N,N-dihydrocarbylacrylamides such asN,N-dimethylacrylamide, N,N-diethylacrylamide, andN-methyl-N-ethylacrylamide; and N,N-dihydrocarbylmethacrylamides such asN,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, andN-methyl-N-ethylmethacrylamide.

Examples of the compound represented by the formula (IIIa) in which R³⁴is a hydrogen atom include N,N-dihydrocarbylformamides such asN,N-dimethylformamide, N,N-dimethylformamide, andN-methyl-N-ethylformamide.

Preferable examples of the compound represented by the formula (III)include a compound represented by the formula (III) in which k is 0; andR³⁴ is bonded with R³¹ to form a divalent group, represented by thefollowing formula (IIIb):

wherein R³² represents an optionally substituted hydrocarbyl group; andR³⁶ represents a hydrocarbylene group, or a group in which ahydrocarbylene group and a group represented by —NR³⁵— are bonded, whereR³⁵ represents a hydrocarbyl group or a hydrogen atom.

In the formula (IIIb), description and examples of an optionallysubstituted hydrocarbyl group for R³² are the same as those stated inthe description of the formula (III).

In the formula (IIIb), examples of the hydrocarbylene group for R³⁶include alkylene groups such as a trimethylene group, a tetramethylenegroup, a pentamethylene group, a hexamethylene group, apentan-2-en-1,5-diyl group, and a 2,2,4-trimethylhexane-1,6-diyl group;and arylene groups such as a 1,4-phenylene group. Examples of the groupin which a hydrocarbylene group and a group represented by —NR³⁵— (R³⁵represents a hydrocarbyl group or a hydrogen atom) are bonded for R³⁶include a group represented by —(CH₂)_(p)—NR³⁵— (R³⁵ represents ahydrocarbyl group or a hydrogen atom, and p represents an integer of 1or more).

In the formula (IIIb), R³² is preferably a C₁₋₁₀ hydrocarbyl group, morepreferably a C₁₋₁₀ alkyl group or a C₆₋₁₀ aryl group, still morepreferably a C₁₋₆ alkyl group or a phenyl group, and particularlypreferably a methyl group, an ethyl group, or a phenyl group.

In the formula (IIIb), R³⁶ is preferably a C₁₋₁₀ hydrocarbylene group,or a group in which a C₁₋₁₀ hydrocarbylene group and a group representedby —NR³⁵— (R³⁵ represents a hydrocarbyl group (preferably a C₁₋₁₀hydrocarbyl group) or a hydrogen atom) are bonded, more preferably aC₃₋₆ alkylene group or a group represented by —(CH₂)_(p)—NR³⁵— (R³⁵represents a hydrocarbyl group (preferably a C₁₋₁₀ hydrocarbyl group),and p represents an integer of not less than 1 (preferably an integer of2 to 5)), and further preferably a trimethylene group, a tetramethylenegroup, a pentamethylene group, or a group represented by—(CH₂)₂—N(CH₃)—.

Examples of the compound represented by the formula (IIIb) in which R³⁶is a hydrocarbylene group include N-hydrocarbyl-β-propiolactams such asN-methyl-β-propiolactam and N-phenyl-β-propiolactam;N-hydrocarbyl-2-pyrrolidones such as N-methyl-2-pyrrolidone,N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone,N-tert-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone;N-hydrocarbyl-2-piperidones such as N-methyl-2-piperidone,N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-hydrocarbyl-ε-caprolactams such as N-methyl-ε-caprolactam andN-phenyl-ε-caprolactam; and N-hydrocarbyl-ω-laurilolactams such asN-methyl-ω-laurilolactam and N-vinyl-ω-laurilolactam.N-phenyl-2-pyrrolidone and N-methyl-ε-caprolactam are preferable amongthe above examples.

Examples of the compound represented by the formula (IIIb) in which R³⁶is a group in which a hydrocarbylene group and a group represented by—NR³⁵— (R³⁵ is a hydrocarbyl group or a hydrogen atom) are bondedinclude 1,3-dihydrocarbyl-2-imidazolidinones such as1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone,1,3-divinyl-2-imidazolidinone, and 1-methyl-3-ethyl-2-imidazolidinone.Among the above examples, 1,3-dimethyl-2-imidazolidinone is preferred.

Preferable examples of the compound represented by the formula (III)include a compound represented by the formula (III) in which k is 1; andR³³ is a hydrocarbylene group, represented by the following formula(IIIc):

wherein R³¹ represents an optionally substituted hydrocarbyl group, oris bonded with R³² to form a hydrocarbylene group optionally containing,as a hetero atom, a nitrogen atom and/or an oxygen atom; R³² representsan optionally substituted hydrocarbyl group, or is bonded with R³¹ toform a hydrocarbylene group optionally containing, as a hetero atom, anitrogen atom and/or an oxygen atom; R³³ represents a hydrocarbylenegroup, and R³⁴ represents an optionally substituted hydrocarbyl group ora hydrogen atom.

In the formula (IIIc), description and examples of the optionallysubstituted hydrocarbyl group for R³¹, R³² or R³⁴; the hydrocarbylenegroup optionally containing, as a hetero atom, a nitrogen atom and/or anoxygen atom, formed by bonding of R³¹ and R³²; and the hydrocarbylenegroup for R³³ are the same as those stated in the description of theformula (III).

In the formula (IIIc), R³³ is preferably a C₁₋₁₀ hydrocarbylene group,more preferably a C₁₋₁₀ alkylene group or a C₆₋₁₀ arylene group, stillmore preferably a C₁₋₆ alkylene group or a phenylene group, andparticularly preferably an ethylene group, a trimethylene group, or a1,4-phenylene group.

In the formula (IIIc), R³⁴ is preferably a C₁₋₁₀ hydrocarbyl group, or asubstituted C₁₋₁₀ hydrocarbyl group in which the substituent is adialkylamino group, more preferably a C₁₋₆ alkyl group, a C₆₋₁₀ arylgroup, a C₁₋₆ dialkylaminoalkyl group, or a C₆₋₁₀ dialkylaminoarylgroup, and still more preferably a methyl group, an ethyl group, aphenyl group, a 3-dimethylaminoethyl group, or a 4-diethylaminophenylgroup.

In the formula (IIIc), R³¹ is preferably a C₁₋₁₀ hydrocarbyl group, oris bonded with R³² to form a C₃₋₁₀ hydrocarbylene group, or a heteroatom-containing C₃₋₁₀ hydrocarbylene group in which the hetero atom is anitrogen atom or an oxygen atom; more preferably a C₁₋₁₀ alkyl group ora C₆₋₁₀ aryl group, or is bonded with R³² to form a C₃₋₁₀ alkylenegroup, a group represented by —CH═N—CH═CH—, a group represented by—CH═N—CH₂—CH₂—, or a group represented by —(CH₂)₂—O—(CH₂)₂—; still morepreferably a C₁₋₆ alkyl group, or is bonded with R³² to form a C₃₋₆alkylene group, a group represented by —CH═N—CH═CH—, or a grouprepresented by —CH═N—CH₂—CH₂—; and particularly preferably a methylgroup or an ethyl group, or is bonded with R³² to form a tetramethylenegroup, a hexamethylene group, or a group represented by —CH═N—CH═CH—.

In the formula (IIIc), R³² is preferably a C₁₋₁₀ hydrocarbyl group, oris bonded with R³¹ to form a C₃₋₁₀ hydrocarbylene group, or a heteroatom-containing C₃₋₁₀ hydrocarbylene group in which the hetero atom is anitrogen atom or an oxygen atom; more preferably a C₁₋₁₀ alkyl group ora C₆₋₁₀ aryl group, or is bonded with R³¹ to form a C₃₋₁₀ alkylenegroup, a group represented by —CH═N—CH═CH—, a group represented by—CH═N—CH₂—CH₂—, or a group represented by —(CH₂)₂—O—(CH₂)₂—; still morepreferably a C₁₋₆ alkyl group, or is bonded with R³¹ to form a C₃₋₆alkylene group, a group represented by —CH═N—CH═CH—, or a grouprepresented by —CH═N—CH₂—CH₂—; and particularly preferably a methylgroup or an ethyl group, or is bonded with R³¹ to form a tetramethylenegroup, a hexamethylene group, or a group represented by —CH═N—CH═CH—.

Examples of the compound represented by the formula (IIIc) in which R³⁴is a hydrocarbyl group include 4-N,N-dihydrocarbylaminoacetophenonessuch as 4-(N,N-dimethylamino)acetophenone,4-N-methyl-N-ethylaminoacetophenone, and 4-N,N-diethylaminoacetophenone;and 4-cyclic aminoacetophenone compounds such as4′-(imidazol-1-yl)acetophenone and 4-pyrazolylacetophenone. Among theabove examples, a 4-cyclic aminoacetophenone compound is preferable, and4′-(imidazol-1-yl)acetophenone is more preferable.

Examples of the compound represented by the formula (IIIc) in which R³⁴is a substituted hydrocarbyl group includebis(dihydrocarbylaminoalkyl)ketones such as1,7-bis(methylethylamino)-4-heptanone and1,3-bis(diphenylamino)-2-propanone; 4-(dihydrocarbylamino)benzophenonessuch as 4-N,N-dimethylaminobenzophenone,4-N,N-di-t-butylaminobenzophenone, and 4-N,N-diphenylaminobenzophenone;and 4,4′-bis(dihydrocarbylamino)benzophenones such as4,4′-bis(dimethylamino)benzophenone, 4,4′-bis(diethylamino)benzophenone,and 4,4′-bis(diphenylamino)benzophenone. Among the above examples,4,4′-bis(dihydrocarbylamino)benzophenone is preferable, and4,4′-bis(diethylamino)benzophenone is more preferable.

Preferable examples of the compound represented by the formula (III)include a compound represented by the formula (III) in which k is 1, andR³³ is a group in which a hydrocarbylene group and an oxygen atom arebonded, or a group in which a hydrocarbylene group and a grouprepresented by —NR³⁵— (R³⁵ represents a hydrocarbyl group or a hydrogenatom) are bonded, represented by the following formula (IIId):

wherein R³¹ represents an optionally substituted hydrocarbyl group, oris bonded with R³² to form a hydrocarbylene group optionally containing,as a hetero atom, a nitrogen atom and/or an oxygen atom; R³² representsan optionally substituted hydrocarbyl group, or is bonded with R³¹ toform a hydrocarbylene group optionally containing, as a hetero atom, anitrogen atom and/or an oxygen atom; R³⁷ represents a hydrocarbylenegroup; A represents an oxygen atom or —NR³⁵— wherein R³⁵ represents ahydrocarbyl group or a hydrogen atom; and R³⁴ represents an optionallysubstituted hydrocarbyl group or a hydrogen atom.

In the formula (IIId), description and examples of the optionallysubstituted hydrocarbyl group for R³¹, R³² or R³⁴, and thehydrocarbylene group optionally containing, as a hetero atom, a nitrogenatom and/or an oxygen atom, formed by bonding of R³¹ and R³², are thesame as those stated in the description of the formula (III). Thehydrocarbyl group for R³⁵ is the same as the hydrocarbyl group for R³¹,R³², or R³⁴.

In the formula (IIId), A is preferably an oxygen atom or a grouprepresented by —NR³⁵— (R³⁵ is a hydrocarbyl group (preferably a C₁₋₅hydrocarbyl group) or a hydrogen atom), more preferably an oxygen atomor a group represented by —NH—, and still more preferably a grouprepresented by —NH—.

In the formula (IIId), examples of the hydrocarbylene group for R³⁷include alkylene groups such as a trimethylene group, a tetramethylenegroup, a pentamethylene group, a hexamethylene group, apentan-2-en-1,5-diyl group, and a 2,2,4-trimethylhexane-1,6-diyl group;and arylene groups such as a 1,4-phenylene group.

In the formula (IIId), R³⁴ is preferably a C₁₋₁₀ hydrocarbyl group, morepreferably an alkenyl group having 2 to 5 carbon atoms, and still morepreferably a vinyl group.

In the formula (IIId), R³⁷ is preferably a C₁₋₁₀ hydrocarbylene group,more preferably a C₁₋₆ alkylene group, still more preferably an ethylenegroup or a trimethylene group, and particularly preferably atrimethylene group.

In the formula (IIId), R³¹ is preferably a C₁₋₁₀ hydrocarbyl group, oris bonded with R³² to form a C₃₋₁₀ hydrocarbylene group, or a heteroatom-containing C₃₋₁₀ hydrocarbylene group in which the hetero atom is anitrogen atom or an oxygen atom; more preferably a C₁₋₁₀ alkyl groupalkylene group, a group represented by —CH═N—CH═CH—, a group representedby —CH═N—CH₂—CH₂—, or a group represented by —(CH₂)₂—O—(CH₂)₂—; stillmore preferably a C₁₋₆ alkyl group, or is bonded with R³² to form a C₃₋₆alkylene group, a group represented by —CH═N—CH═CH—, or a grouprepresented by —CH═N—CH₂—CH₂—; and particularly preferably a methylgroup or an ethyl group, or is bonded with R³² to form a tetramethylenegroup, a hexamethylene group, or a group represented by —CH═N—CH═CH—.

In the formula (IIId), R³² is preferably a C₁₋₁₀ hydrocarbyl group, oris bonded with Rn to form a C₃₋₁₀ hydrocarbylene group, or a heteroatom-containing C₃₋₁₀ hydrocarbylene group in which the hetero atom is anitrogen atom or an oxygen atom; more preferably a C₁₋₁₀ alkyl group ora C₆₋₁₀ aryl group, or is bonded with R³¹ to form a C₃₋₁₀ alkylenegroup, a group represented by —CH═N—CH═CH—, a group represented by—CH═N—CH₂—CH₂—, or a group represented by —(CH₂)₂—O—(CH₂)₂—; still morepreferably a C₁₋₆ alkyl group, or is bonded with R³¹ to form a C₃₋₆alkylene group, a group represented by —CH═N—CH═CH—, or a grouprepresented by —CH═N—CH₂—CH₂—; and particularly preferably a methylgroup or an ethyl group, or is bonded with R³¹ to form a tetramethylenegroup, a hexamethylene group, or a group represented by —CH═N—CH═CH—.

Examples of the compound represented by the formula (IIId) in which A isan oxygen atom include 2-N,N-dihydrocarbylaminoethyl acrylates such as2-N,N-dimethylaminoethyl acrylate and 2-N,N-diethylaminoethyl acrylate;3-N,N-dihydrocarbylaminopropyl acrylates such as3-N,N-dimethylaminopropyl acrylate; 2-N,N-dihydrocarbylaminoethylmethacrylates such as 2-N,N-dimethylaminoethyl methacrylate and2-N,N-diethylaminoethyl methacrylate; and 3-N,N-dihydrocarbylaminopropylmethacrylates such as 3-N,N-dimethylaminopropyl methacrylate. Thecompound is preferably 3-N,N-dihydrocarbylaminopropyl acrylate, and morepreferably 3-N,N-dimethylaminopropyl acrylate.

Examples of the compound represented by the formula (IIId) in which A isa group represented by —NR³⁵— (R³⁵ is a hydrocarbyl group or a hydrogenatom) include N,N-dihydrocarbylaminoethylacrylamides such asN,N-dimethylaminoethylacrylamide and N,N-diethylaminoethylacrylamide;N,N-dihydrocarbylaminopropylacrylamides such asN,N-dimethylaminopropylacrylamide and N,N-diethylaminopropylacrylamide;N,N-dihydrocarbylaminobutylacrylamides such asN,N-dimethylaminobutylacrylamide and N,N-diethylaminobutylacrylamide;N,N-dihydrocarbylaminoethylmethacrylamides such asN,N-dimethylaminoethylmethacrylamide andN,N-diethylaminoethylmethacrylamide;N,N-dihydrocarbylaminopropylmethacrylamides such asN,N-dimethylaminopropylmethacrylamide andN,N-diethylaminopropylmethacrylamide; andN,N-dihydrocarbylaminobutylmethacrylamides such asN,N-dimethylaminobutylmethacrylamide andN,N-diethylaminobutylmethacrylamide. The compound is preferablyN,N-dihydrocarbylaminopropylacrylamide, and more preferablyN,N-dimethylaminopropylacrylamide.

The compound represented by the formula (III) is preferably a compoundrepresented by the formula (IIId), particularly preferablyN,N-dihydrocarbylaminopropylacrylamide, and most preferablyN,N-dimethylaminopropylacrylamide.

In addition to those described above, preferable examples of thecompound containing a nitrogen atom and/or a silicon atom include analkoxysilyl group-containing compound.

The alkoxysilyl group-containing compound is preferably a compoundcontaining a nitrogen atom and an alkoxysilyl group, and more preferablya compound represented by the following formula (IV):

wherein R⁴¹ represents a hydrocarbyl group; R⁴² and R⁴³ each represent ahydrocarbyl group or a hydrocarbyloxy group; R⁴⁴ represents anoptionally substituted hydrocarbyl group or a trihydrocarbylsilyl group,or is bonded with R⁴⁵ to form a hydrocarbylene group optionallycontaining, as a hetero atom, at least one selected from the groupconsisting of a silicon atom, a nitrogen atom and an oxygen atom; R⁴⁵represents an optionally substituted hydrocarbyl group or atrihydrocarbylsilyl group, or is bonded with R⁴⁴ to form ahydrocarbylene group optionally containing, as a hetero atom, at leastone selected from the group consisting of a silicon atom, a nitrogenatom and an oxygen atom; and j represents an integer of 1 to 5.

In the formula (IV), the optionally substituted hydrocarbyl group is ahydrocarbyl group or a substituted hydrocarbyl group. Examples of thehydrocarbyl group include alkyl groups such as a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, and an n-butyl group;alkenyl groups such as a vinyl group, an allyl group, and an isopropenylgroup; and aryl groups such as a phenyl group. The hydrocarbyl group ispreferably an alkyl group, and more preferably a methyl group or anethyl group. Examples of the substituted hydrocarbyl group includeoxacycloalkyl groups such as an oxiranyl group and a tetrahydrofuranylgroup, and preferably a tetrahydrofuranyl group.

Herein, the oxacycloalkyl group represents a group in which CH₂ on analicycle of a cycloalkyl group is replaced with an oxygen atom.

Examples of the hydrocarbyloxy group include alkoxy groups such as amethoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group,an n-butoxy group, a sec-butoxy group, and a tert-butoxy group; andaryloxy groups such as a phenoxy group and a benzyloxy group. Thehydrocarbyloxy group is preferably an alkoxy group, and more preferablya methoxy group or an ethoxy group.

Examples of the trihydrocarbylsilyl group include a trimethylsilyl groupand a tert-butyl-dimethylsilyl group, and preferably a trimethylsilylgroup.

The hydrocarbylene group optionally containing, as a hetero atom, atleast one selected from the group consisting of a silicon atom, anitrogen atom and an oxygen atom is a hydrocarbylene group, or a heteroatom-containing hydrocarbylene group in which the hetero atom is atleast one selected from the group consisting of a silicon atom, anitrogen atom and an oxygen atom. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is at least one selectedfrom the group consisting of a silicon atom, a nitrogen atom and anoxygen atom include a hetero atom-containing hydrocarbylene group inwhich the hetero atom is a silicon atom, a hetero atom-containinghydrocarbylene group in which the hetero atom is a nitrogen atom, and ahetero atom-containing hydrocarbylene group in which the hetero atom isan oxygen atom. Examples of the hydrocarbylene group include alkylenegroups such as a tetramethylene group, a pentamethylene group, ahexamethylene group, a pentan-2-en-1,5-diyl group, and a2,2,4-trimethylhexane-1,6-diyl group. Among them, a C₄₋₇ alkylene groupis preferable, and a pentamethylene group or a hexamethylene group ismore preferable. Examples of the hetero atom-containing hydrocarbylenegroup in which the hetero atom is a silicon atom include a grouprepresented by —Si(CH₃)₂—CH₂—CH₂—Si(CH₃)₂—. Examples of the heteroatom-containing hydrocarbylene group in which the hetero atom is anitrogen atom include a group represented by —CH═N—CH═CH—, or a grouprepresented by —CH═N—CH₂—CH₂—. Examples of the hetero atom-containinghydrocarbylene group in which the hetero atom is an oxygen atom includea group represented by —CH₂—CH₂—O—CH₂—CH₂—.

In the formula (IV), R⁴¹ is preferably a C₁₋₄ alkyl group, and morepreferably a methyl group or an ethyl group. R⁴² and R⁴³ each arepreferably a hydrocarbyloxy group, more preferably a C₁₋₄ alkoxy group,and still more preferably a methoxy group or an ethoxy group. R⁴⁴ andR⁴⁵ each are preferably a hydrocarbyl group, more preferably a C₁₋₄alkyl group, and still more preferably a methyl group or an ethyl group.Here, j is preferably an integer of 2 to 4.

Examples of the compound represented by the formula (IV) include[(dialkylamino)alkyl]alkoxysilane compounds such as3-dimethylaminopropyltriethoxysilane,3-dimethylaminopropyltrimethoxysilane,3-diethylaminopropyltriethoxysilane,3-diethylaminopropyltrimethoxysilane,3-dimethylaminopropylmethyldiethoxysilane,2-dimethylaminoethyltriethoxysilane, and2-dimethylaminoethyltrimethoxysilane; cyclic aminoalkylalkoxysilanecompounds such as hexamethyleneiminomethyltrimethoxysilane,3-hexamethyleneiminopropyltriethoxysilane,N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, andN-(3-trimethoxysilylpropyl)-4,5-imidazole;[di(tetrahydrofuranyl)amino]alkylalkoxysilane compounds such as3-[di(tetrahydrofuranyl)amino]propyltrimethoxysilane and3-[di(tetrahydrofuranyl)amino]propyltriethoxysilane; andN,N-bis(trialkylsilyl)aminoalkylalkoxysilane compounds such asN,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane andN,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane. Among the aboveexamples, [(dialkylamino)alkyl]alkoxysilane compounds are preferable,and 3-dimethylaminopropyltriethoxysilane,3-dimethylaminopropyltrimethoxysilane,3-diethylaminopropyltriethoxysilane, and3-diethylaminopropyltrimethoxysilane are more preferable.

Examples of the compound containing an alkoxysilyl group, in addition tothe aforementioned compounds containing a nitrogen atom and analkoxysilyl group, include tetraalkoxysilanes such astetramethoxysilane, tetraethoxysilane, and tetra-n-propoxysilane;trialkoxyhydrocarbylsilanes such as methyltrimethoxysilane,methyltriethoxysilane, ethyltrimethoxysilane, andphenyltrimethoxysilane; trialkoxyhalosilanes such astrimethoxychlorosilane, triethoxychlorosilane, andtri-n-propoxychlorosilane; dialkoxydihydrocarbylsilanes such asdimethoxydimethylsilane, diethoxydimethylsilane, anddimethoxydiethylsilane; dialkoxydihalosilanes such asdimethoxydichlorosilane, diethoxydichlorosilane, anddi-n-propoxydichlorosilane; monoalkoxytrihydrocarbylsilanes such asmethoxytrimethylsilane; monoalkoxytrihalosilanes such asmethoxytrichlorosilane and ethoxytrichlorosilane;(glycidoxyalkyl)alkoxysilane compounds such as2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane,(2-glycidoxyethyl)methyldimethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and(3-glycidoxypropyl)methyldimethoxysilane;(3,4-epoxycyclohexyl)alkylalkoxysilane compounds such as2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane;alkoxysilylalkylsuccinic acid anhydrides such as3-trimethoxysilylpropylsuccinic acid anhydride and3-triethoxysilylpropylsuccinic acid anhydride; and(methacryloyloxyalkyl)alkoxysilane compounds such as3-methacryloyloxypropyltrimethoxysilane and3-methacryloyloxypropyltriethoxysilane.

The compound containing an alkoxysilyl group may contain a nitrogen atomand a carbonyl group. Examples of the compound containing a nitrogenatom and a carbonyl group as well as an alkoxysilyl group includetris[(alkoxysilyl)alkyl]isocyanurate compounds such astris[3-(trimethoxysilyl)propyl]isocyanurate,tris[3-(triethoxysilyl)propyl]isocyanurate,tris[3-(tripropoxysilyl)propyl]isocyanurate, andtris[3-(tributoxysilyl)propyl]isocyanurate. Among them,tris[3-(trimethoxysilyl)propyl]isocyanurate is preferable.

Examples of the compound containing a nitrogen atom and/or a siliconatom include an N,N-dialkyl-substituted carboxylic acid amide dialkylacetal compound. Examples of the N,N-dialkyl-substituted carboxylic acidamide dialkyl acetal compound include N,N-dialkylformamide dialkylacetals such as N,N-dimethylformamide dimethyl acetal andN,N-diethylformamide dimethyl acetal; N,N-dialkylacetamide dialkylacetals such as N,N-dimethylacetamide dimethyl acetal andN,N-diethylacetamide dimethyl acetal; and N,N-dialkylpropionamidedialkyl acetals such as N,N-dimethylpropionamide dimethyl acetal andN,N-diethylpropionamide dimethyl acetal. Among them,N,N-dialkylformamide dialkyl acetals are preferable, andN,N-dimethylformamide dimethyl acetals are more preferable.

In a method of producing the conjugated diene polymer, a coupling agentmay be added to a solution of the conjugated diene polymer in ahydrocarbon at a time from initiation of the polymerization of monomersuntil recovery of a polymer described later. Examples of the couplingagent include a compound represented by the following formula (V):R⁵¹ _(a)ML_(4-a)  (V)wherein R⁵¹ represents an alkyl group, an alkenyl group, a cycloalkenylgroup, or an aryl group; M represents a silicon atom or a tin atom; Lrepresents a halogen atom or a hydrocarbyloxy group; and a represents aninteger of 0 to 2.

Examples of the coupling agent represented by the formula (V) includesilicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane,trimethylchlorosilane, tin tetrachloride, methyltrichlorotin,dimethyldichlorotin, trimethylchlorotin, tetramethoxysilane,methyltrimethoxysilane, dimethoxydimethylsilane, methyltriethoxysilane,ethyltrimethoxysilane, dimethoxydiethylsilane, diethoxydimethylsilane,tetraethoxysilane, ethyltriethoxysilane, and diethoxydiethylsilane.

For enhancing the processability of the conjugated diene polymer, theamount of the coupling agent to be added is preferably not less than0.03 mol and more preferably not less than 0.05 mol, per mol of analkali metal derived from an alkali metal catalyst. For enhancing thefuel economy, the amount is preferably not more than 0.4 mol and morepreferably not more than 0.3 mol.

In the method of producing the conjugated diene polymer, an unreactedactive terminal may be treated with alcohol, such as methanol orisopropyl alcohol, before recovery of a polymer described later.

As a method of recovering a conjugated diene polymer from the solutionof the conjugated diene polymer in a hydrocarbon, known methods may beemployed. Examples of the method include (A) a method of adding acoagulant to the solution of the conjugated diene polymer in ahydrocarbon, and (B) a method of adding steam to the solution of theconjugated diene polymer in a hydrocarbon solvent (steam strippingtreatment). The recovered conjugated diene polymer may be dried with aknown dryer, such as a band dryer or an extrusion-type dryer.

For achieving a balanced enhancement in processability, fuel economy,rubber strength, abrasion resistance, wet-grip performance, and handlingstability, the amount of the structural unit derived from thepolymerization initiator represented by the formula (I) in theconjugated diene polymer, when expressed per unit mass of the polymer,is preferably not less than 0.0001 mmol/g polymer, and more preferablynot less than 0.001 mmol/g polymer, but is preferably not more than 0.15mmol/g polymer, and more preferably not more than 0.1 mmol/g polymer.

For achieving a balanced enhancement in processability, fuel economy,rubber strength, abrasion resistance, wet-grip performance, and handlingstability, the amount of the structural unit derived from thesilicon-containing vinyl compound in the conjugated diene polymer, whenexpressed per unit mass of the polymer, is preferably not less than 0.01mmol/g polymer, and more preferably not less than 0.02 mmol/g polymer,but is preferably not more than 0.4 mmol/g polymer, and more preferablynot more than 0.2 mmol/g polymer.

For achieving a balanced enhancement in processability, fuel economy,rubber strength, abrasion resistance, wet-grip performance, and handlingstability, the conjugated diene polymer preferably contains a structuralunit derived from the compound represented by the formula (II). Thestructural unit derived from the compound represented by the formula(II) in the conjugated diene polymer refers to a structural unitrepresented by the following formula (IIb):

wherein m, R²¹, X¹, X², and X³ are the same as those stated in thedescription of the formula (II).

In the conjugated diene polymer according to the present invention,preferably, at least one of X¹, X² and X³ is replaced by a hydroxylgroup, more preferably two or more of X¹, X² and X³ are replaced byhydroxyl groups, and still more preferably two of X¹, X² and X³ arereplaced by hydroxyl groups, in the structural unit derived from thecompound represented by the formula (II). This enables to enhance theeffect of enhancing the processability, fuel economy, rubber strength,abrasion resistance, wet-grip performance, and handling stability.Unlimited examples of a method of replacing at least one of X¹, X², andX³ with a hydroxyl group include steam stripping treatment.

For achieving a balanced enhancement in processability, fuel economy,rubber strength, abrasion resistance, wet-grip performance, and handlingstability, the conjugated diene polymer preferably contains a structuralunit (aromatic vinyl unit) derived from an aromatic vinyl compound. Ifthe conjugated diene polymer contains an aromatic vinyl unit, the amountof the aromatic vinyl compound in the conjugated diene polymer based on100% by mass of the combined amount of the structural unit (conjugateddiene unit) derived from the conjugated diene compound and the aromaticvinyl unit is preferably not less than 10% by mass (the amount of theconjugated diene unit is not more than 90% by mass), and more preferablynot less than 15% by mass (the amount of the conjugated diene unit isnot more than 85% by mass). Also, from the viewpoint of the fueleconomy, the amount of the aromatic vinyl unit is preferably not morethan 50% by mass (the amount of the conjugated diene unit is not lessthan 50% by mass), and more preferably not more than 45% by mass (theamount of the conjugated diene unit is not less than 55% by mass).

If the conjugated diene polymer contains a structural unit derived froman aromatic vinyl compound, for enhancing the fuel economy, the vinylbond content (vinyl content) in the conjugated diene polymer ispreferably not more than 80 mol %, and more preferably not more than 70mol %, based on the amount of the conjugated diene unit (regarded as 100mol %). From the viewpoint of the wet-grip performance, the vinyl bondcontent is preferably not less than 10 mol %, more preferably not lessthan 15 mol %, still more preferably not less than 20 mol %, andparticularly preferably not less than 40 mol %.

In particular, for enhancing the abrasion resistance, the conjugateddiene polymer preferably contains no structural unit derived from anaromatic vinyl compound. In this case, the vinyl bond content (vinylcontent) in the conjugated diene polymer is preferably not more than 20mol %, and more preferably not more than 15 mol %, based on the amountof the conjugated diene unit (regarded as 100 mol %).

The vinyl bond content in the conjugated diene polymer is measured bythe method described in examples below.

For enhancing the fuel economy, the molecular weight distribution of theconjugated diene polymer is preferably 1 to 5, and more preferably 1 to2. The molecular weight distribution is obtained by measuring anumber-average molecular weight (Mn) and a weight-average molecularweight (Mw) using gel permeation chromatography (GPC), and dividing Mwby Mn.

The conjugated diene polymer may be used as a rubber component in therubber composition of the present invention.

The amount of the conjugated diene polymer based on 100% by mass of therubber component is not more than 90% by mass, preferably not more than80% by mass, and more preferably not more than 75% by mass. An amount ofmore than 90% by mass tends to not only decrease the abrasion resistancebut also drive up the cost. The amount of the conjugated diene polymeris not less than 1% by mass, preferably not less than 5% by mass, morepreferably not less than 10% by mass, still more preferably not lessthan 25% by mass, and particularly preferably not less than 55% by mass.An amount of less than 1% by mass tends not to easily improve the fueleconomy.

The rubber composition of the present invention includesstyrene-butadiene rubber (SBR). Examples of the SBR include theconjugated diene polymer synthesized as a modified SBR, and SBRs usuallyused in the tire industry such as Nipol NS116R (produced by produced byZEON Corporation).

The amount of SBR based on 100% by mass of the rubber component is notless than 35% by mass, and preferably not less than 45% by mass. If theamount is less than 35% by mass, the handling stability on dry roadsurfaces or wet-grip performance may not be sufficiently improved. Theamount of SBR may be 100% by mass, but is preferably not more than 80%by mass, and more preferably not more than 75% by mass. If the amountexceeds 80% by mass, the fuel economy may decrease.

The amount of SBR refers to the total amount of modified SBRs andunmodified SBRs.

The other rubber component to be used together with the conjugated dienepolymer may suitably be a polyisoprene-based rubber. If apolyisoprene-based rubber is added, the rubber strength increases, andthe cohesion of the rubber compound during mixing is enhanced so thatproductivity can be improved.

Examples of the polyisoprene-based rubber include natural rubber (NR),and polyisoprene rubber (IR). The NR is not particularly limited, andexamples thereof include those usually used in the tire industry, suchas SIR20, RSS#3, TSR20, deproteinized natural rubber (DPNR), highlypurified natural rubber (HPNR), and epoxidized natural rubber (ENR).Similarly, IRs usually used in the tire industry may be used.

In the case where the rubber composition of the present inventionincludes a polyisoprene-based rubber, the amount of thepolyisoprene-based rubber based on 100% by mass of the rubber componentis preferably not less than 10% by mass, and more preferably not lessthan 15% by mass. If the amount is less than 10% by mass, the rubberstrength may decrease and the cohesion of the rubber compound duringmixing may be so poor that productivity can be deteriorated. The amountof the polyisoprene-based rubber is not more than 40% by mass, andpreferably not more than 25% by mass. If the amount of thepolyisoprene-based rubber exceeds 40% by mass, sufficient wet-gripperformance may not be achieved.

Examples of materials that can be used in the rubber component, otherthan polyisoprene-based rubbers, include polybutadiene rubber (BR),butadiene-isoprene copolymer rubber, and butyl rubber.Ethylene-propylene copolymers, and ethylene-octene copolymers may alsobe mentioned. Two or more kinds of the rubber materials may be used incombination. From the viewpoint of achieving a balanced improvement inprocessability, fuel economy, rubber strength, abrasion resistance,wet-grip performance, and handling stability, a rubber componentcontaining not less than 50% by mass of a structural unit derived from aconjugated diene compound is preferably used. Specifically, BR ispreferred.

The BR is not particularly limited, and examples thereof include BRsusually used in the tire industry. For example, BRs with a high ciscontent such as BR1220 (produced by ZEON Corporation), and BR130B andBR150B (produced by Ube Industries, Ltd.); and syndiotacticpolybutadiene crystal-containing BRs such as VCR412 and VCR617 (producedby Ube Industries, Ltd.) may be used.

If the rubber composition of the present invention contains BR, theamount of BR based on 100% by mass of the rubber component is preferablynot less than 5% by mass, more preferably not less than 10% by mass, andstill more preferably not less than 15% by mass. If the amount is lessthan 5% by mass, the abrasion resistance tends to decrease. The amountof BR is preferably not more than 60% by mass, more preferably not morethan 50% by mass, still more preferably not more than 40% by mass, andparticularly preferably not more than 30% by mass. If the amount is morethan 60% by mass, the wet grip performance tends to decrease.

The rubber composition of the present invention contains silica having anitrogen adsorption specific surface area (N₂SA) of 40 to 400 m²/g.Unlimited examples of the silica include dry silica (anhydrous silica)and wet silica (hydrous silica). Wet silica is preferable because it hasmore silanol groups.

The silica has a nitrogen adsorption specific surface area (N₂SA) of notless than 40 m²/g, preferably not less than 50 m²/g, and more preferablynot less than 60 m²/g. If the silica has a N₂SA of less than 40 m²/g,the silica tends to have little reinforcement, and thus the abrasionresistance and rubber strength tend to decrease. The silica has a N₂SAof not more than 400 m²/g, preferably not more than 360 m²/g, and morepreferably not more than 300 m²/g. Silica having a N₂SA of more than 400m²/g tends not to disperse easily, and thus the fuel economy andprocessability tend to deteriorate.

The N₂SA of silica is determined by the BET method in accordance withASTM D3037-93.

The amount of the silica (total amount if two or more kinds of silicaare used) for each 100 parts by mass of the rubber component is not lessthan 10 parts by mass, preferably not less than 30 parts by mass, andmore preferably not less than 45 parts by mass. If the amount is lessthan 10 parts by mass, the effect producible by blending silica tendsnot to be sufficiently achieved, and the abrasion resistance and rubberstrength tend to decrease. The amount of the silica is not more than 150parts by mass, and preferably not more than 100 parts by mass. If theamount exceeds 150 parts by mass, the processability tends todeteriorate.

One kind of silica may solely be used, but preferably two or more kindsof silica are used in combination. A combination use of silica (1)having a nitrogen adsorption specific surface area of at least 50 m²/gbut less than 120 m²/g, and silica (2) having a nitrogen adsorptionspecific surface area of not less than 120 m²/g is more preferable. Ifthe silica (1) and the silica (2) are mixed with the conjugated dienepolymer, the silica (1) and the silica (2) disperse well so that theeffect of improving the properties can be synergistically enhanced.Moreover, if the silica (1) and the silica (2) are used together with amercapto group-containing silane coupling agent or a specific solidresin, which is described later, the effect of improving the propertiescan further be enhanced.

The silica (1) and the silica (2) preferably satisfy the inequality:(N₂SA of silica (2))/(N₂SA of silica (1))≧1.4, and more preferablysatisfy the inequality: (N₂SA of silica (2))/(N₂SA of silica (1))≧2.0.If the ratio of (N₂SA of silica (2))/(N₂SA of silica (1)) is less than1.4, the difference in the particle diameter between the silica (1) andthe silica (2) is small. Thus, a dispersibility-improving effectproducible by blending two kinds of silica tends not to be sufficientlyachieved.

The silica (1) has a N₂SA of not less than 50 m²/g, and preferably notless than 70 m²/g. If the silica (1) has a N₂SA of less than 50 m²/g,the silica tends to have an insufficient reinforcement, and the rubberstrength, abrasion resistance, and handling stability may deteriorate.The silica (1) has a N₂SA of less than 120 m²/g, and preferably not morethan 115 m²/g. If the silica (1) has a N₂SA of not less than 120 m²/g,the effect producible by the combination use of the silica (1) and thesilica (2) may not be sufficiently achieved.

The silica (2) has a N₂SA of not less than 120 m²/g, and preferably notless than 150 m²/g. If the silica (2) has a N₂SA of less than 120 m²/g,the effect producible by the combination use of the silica (1) and thesilica (2) may not be sufficiently achieved. The silica (2) has a N₂SAof preferably not more than 250 m²/g, and more preferably not more than220 m²/g. If the silica (2) has a N₂SA of more than 250 m²/g, the fueleconomy and processability tend to deteriorate.

The amounts of the silica (1) and the silica (2) preferably satisfy thefollowing inequality:(Amount of silica (1))×0.06≦(Amount of silica (2))≦(Amount of silica(1))×15.

If the amount of the silica (2) is less than 0.06 times the amount ofthe silica (1), a sufficient rubber strength tends not to be achieved.If the amount of the silica (2) is more than 15 times the amount of thesilica (1), the rolling resistance tends to increase. The amount of thesilica (2) is more preferably not less than 0.3 times the amount of thesilica (1), and still more preferably not less than 0.5 times the amountof the silica (1). Also, the amount of the silica (2) is more preferablynot more than 7 times the amount of the silica (1), and still morepreferably not more than 4 times the amount of the silica (1).

The amount of the silica (1) is preferably not less than 5 parts bymass, and more preferably not less than 10 parts by mass for each 100parts by mass of the rubber component. If the amount of the silica (1)is less than 5 parts by mass, the fuel economy may not be sufficientlyimproved. Also, the amount of the silica (1) is preferably not more than90 parts by mass, and more preferably not more than 70 parts by mass. Ifthe amount of the silica (1) is more than 90 parts by mass, good fueleconomy is achieved, but the rubber strength and abrasion resistancetend to decrease.

The amount of the silica (2) is preferably not less than 5 parts bymass, and more preferably not less than 10 parts by mass for each 100parts by mass of the rubber component. If the amount of the silica (2)is less than 5 parts by mass, sufficient handling stability may not beachieved. Also, the amount of the silica (2) is preferably not more than90 parts by mass, and more preferably not more than 70 parts by mass. Ifthe amount of the silica (2) is more than 90 parts by mass, goodhandling stability is achieved; however, the processability tends todeteriorate.

The total amount of the silica (1) and the silica (2) is preferably notless than 10 parts by mass, more preferably not less than 30 parts bymass, and still more preferably not less than 45 parts by mass for each100 parts by mass of the rubber component. If the total amount is lessthan 10 parts by mass, the effect producible by blending the silica (1)and the silica (2) may not be sufficiently achieved. Thus, the abrasionresistance and rubber strength tend to decrease. The total amount of thesilica (1) and the silica (2) is not more than 150 parts by mass, andpreferably not more than 100 parts by mass. If the total amount exceeds150 parts by mass, the processability tends to deteriorate.

The silica may be used together with a silane coupling agent. From aviewpoint that a combination use of the conjugated diene polymer and thesilica can synergistically improve the properties, preferable examplesof silane coupling agents include mercapto group-containing silanecoupling agents. If a mercapto group-containing silane coupling agent isused together with the silica (1) and the silica (2) or a specific solidresin mentioned later, the effect of improving the properties canfurther be enhanced.

Preferable examples of the mercapto group-containing silane couplingagent include a compound represented by the formula (1) below, and/or acompound containing a linking unit A represented by the formula (2)below and a linking unit B represented by the formula (3) below,

wherein R¹⁰¹ to R¹⁰³ each represent a branched or unbranched C₁₋₁₂ alkylgroup, a branched or unbranched C₁₋₁₂ alkoxy group, or a grouprepresented by —O— (R¹¹¹—O)_(z)—R¹¹² where z R¹¹¹s each represent abranched or unbranched C₁₋₃₀ divalent hydrocarbon group, and z R¹¹¹s maybe the same as or different from one another; R¹¹² represents a branchedor unbranched C₁₋₃₀ alkyl group, a branched or unbranched C₂₋₃₀ alkenylgroup, a C₆₋₃₀ aryl group, or a C₇₋₃₀ aralkyl group; and z represents aninteger of 1 to 30, and R¹⁰¹ to R¹⁰³ may be the same as or differentfrom one another; and R¹⁰⁴ represents a branched or unbranched C₁₋₆alkylene group;

wherein R²⁰¹ represents a hydrogen atom, a halogen atom, a branched orunbranched C₁₋₃₀ alkyl group, a branched or unbranched C₂₋₃₀ alkenylgroup, a branched or unbranched C₂₋₃₀ alkynyl group, or the alkyl groupin which a terminal hydrogen atom is replaced with a hydroxyl group or acarboxyl group; R²⁰² represents a branched or unbranched C₁₋₃₀ alkylenegroup, a branched or unbranched C₂₋₃₀ alkenylene group, or a branched orunbranched C₂₋₃₀ alkynylene group; and R²⁰¹ and R²⁰² may be joinedtogether to form a cyclic structure.

The following describes the compound represented by the formula (I).

The use of the compound represented by the formula (1) allows the silicato disperse well, and thus the effects of the present invention are wellachieved. In particular, the use of the compound represented by theformula (1) can greatly improve the wet grip performance and fueleconomy.

R¹⁰¹ to R¹⁰³ each are a branched or unbranched C₁₋₁₂ alkyl group, abranched or unbranched C₁₋₁₂ alkoxy group, or a group represented by—O—(R¹¹¹—O)_(z)—R¹¹². In view of achieving the effects of the presentinvention well, preferably at least one of R¹⁰¹ to R¹⁰³ is a grouprepresented by —O—(R¹¹¹—O)_(z)—R¹¹², and more preferably two of R¹⁰¹ toR¹⁰³ are groups represented by —O—(R¹¹¹—O)_(z)—R¹¹² and the other is abranched of unbranched C₁₋₁₂ alkoxy group.

Examples of the branched or unbranched C₁₋₁₂ (preferably C₁₋₅) alkylgroup for R¹⁰¹ to R¹⁰³ include a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, an iso-butylgroup, a sec-butyl group, a tert-butyl group, a pentyl group, a hexylgroup, a heptyl group, a 2-ethylhexyl group, an octyl group, and a nonylgroup.

Examples of the branched or unbranched C₁₋₁₂ (preferably C₁₋₅) alkoxygroup for R¹⁰¹ to R¹⁰³ include a methoxy group, an ethoxy group, ann-propoxy group, an isopropoxy group, an n-butoxy group, an iso-butoxygroup, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, ahexyloxy group, a heptyloxy group, a 2-ethylhexyloxy group, an octyloxygroup, and a nonyloxy group.

R¹¹¹ in the group represented by —O—(R¹¹¹—O)_(z)—R¹¹² for R¹⁰¹ to R¹⁰³represents a branched or unbranched C₁₋₃₀ (preferably C₁₋₁₅, morepreferably C₁₋₃) divalent hydrocarbon group.

Examples of the hydrocarbon group include branched or unbranched C₁₋₃₀alkylene groups, branched or unbranched C₂₋₃₀ alkenylene groups,branched or unbranched C₂₋₃₀ alkynylene groups, and branched orunbranched C₆₋₃₀ arylene groups. Branched or unbranched C₁₋₃₀ alkylenegroups are preferred among the examples.

Examples of the branched or unbranched C₁₋₃₀ (preferably C₁₋₁₅, morepreferably C₁₋₃) alkylene group for R¹¹¹ include a methylene group, anethylene group, a propylene group, a butylene group, a pentylene group,a hexylene group, a heptylene group, an octylene group, a nonylenegroup, a decylene group, an undecylene group, a dodecylene group, atridecylene group, a tetradecylene group, a pentadecylene group, ahexadecylene group, a heptadecylene group, and an octadecylene group.

Examples of the branched or unbranched C₂₋₃₀ (preferably C₂₋₁₅, morepreferably C₂₋₃) alkenylene group for R¹¹¹ include a vinylene group, a1-propenylene group, a 2-propenylene group, a 1-butenylene group, a2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, a1-hexenylene group, a 2-hexenylene group, and a 1-octenylene group.

Examples of the branched or unbranched C₂₋₃₀ (preferably C₂₋₁₅, morepreferably C₂₋₃) alkynylene group for R¹¹¹ include an ethynylene group,a propynylene group, a butynylene group, a pentynylene group, ahexynylene group, a heptynylene group, an octynylene group, a nonynylenegroup, a decynylene group, an undecynylene group, and a dodecynylenegroup.

Examples of the C₆₋₃₀ (preferably C₆₋₁₅) arylene group for R¹¹¹ includea phenylene group, a tolylene group, a xylylene group, and a naphthylenegroup.

Here, z represents an integer of 1 to 30 (preferably 2 to 20, morepreferably 3 to 7, and still more preferably 5 or 6).

R¹¹² represents a branched or unbranched C₁₋₃₀ alkyl group, a branchedor unbranched C₂₋₃₀ alkenyl group, a C₆₋₃₀ aryl group, or a C₇₋₃₀aralkyl group. R¹¹² is especially preferably a branched or unbranchedC₁₋₃₀ alkyl group.

Examples of the branched or unbranched C₁₋₃₀ (preferably C₃₋₂₅, morepreferably C₁₀₋₁₅) alkyl group for R¹¹² include a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, an n-butyl group, aniso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group,a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, anonyl group, a decyl group, an undecyl group, a dodecyl group, atridecyl group, a tetradecyl group, a pentadecyl group, and an octadecylgroup.

Examples of the branched or unbranched C₂₋₃₀ (preferably C₃₋₂₅, morepreferably C₁₀₋₁₅) alkenyl group for R¹¹² include a vinyl group, a1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenylgroup, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a2-hexenyl group, a 1-octenyl group, a decenyl group, an undecenyl group,a dodecenyl group, a tridecenyl group, a tetradecenyl group, apentadecenyl group, and an octadecenyl group.

Examples of the C₆₋₃₀ (preferably C₁₀₋₂₀) aryl group for R¹¹² include aphenyl group, a tolyl group, a xylyl group, a naphthyl group, and abiphenyl group.

Examples of the C₇₋₃₀ (preferably C₁₀₋₂₀) aralkyl group for R¹¹² includea benzyl group and a phenethyl group.

Specific examples of the group represented by —O—(R¹¹¹—O)_(z)—R¹¹²include groups represented by —O—(C₂H₄—O)₅—C₁₁H₂₃, —O—(C₂H₄—O)₅—C₁₂R₂₅,—O—(C₂H₄—O)₅—C₁₃H₂₇, —O—(C₂H₄—O)₅—C₁₄H₂₉, —O—(C₂H₄—O)₅—C₁₅H₃₁,—O—(C₂H₄—O)₃—C₁₃H₂₇, —O—(C₂H₄—O)₄—C₁₃H₂₇, —O—(C₂H₄—O)₆—C₁₃H₂₇ and—O—(C₂H₄—O)₇—C₁₃H₂₇. Among the examples, groups represented by—O—(C₂H₄—O)₅—C₁₁H₂₃, —O—(C₂H₄—O)₅—C₁₃H₂₇, —O—(C₂H₄—O)₅—C₁₅H₃₁, and—O—(C₂H₄—O)₆—C₁₃H₂₇ are preferable.

Examples of the branched or unbranched C₁₋₆ (preferably C₁₋₅) alkylenegroup for R¹⁰⁴ include groups as mentioned for the branched orunbranched C₁₋₃₀ alkylene groups for R¹¹¹.

Examples of the compound represented by the formula (1) include3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane,2-mercaptoethyl-trimethoxysilane, 2-mercaptoethyltriethoxysilane, and acompound represented by the following formula (Si363 produced by EvonikDegussa). Use of the compound represented by the following formula ispreferred. Any of these compounds may be used alone or two or more ofthese may be used in combination.

The following describes the compound containing a linking unit Arepresented by the formula (2) and a linking unit B represented by theformula (3).

In the case where the compound containing a linking unit A representedby the formula (2) and a linking unit B represented by the formula (3)is used, the increase in viscosity during the processing is suppressedas compared to the case where polysulfide silane such asbis-(3-triethoxysilylpropyl)tetrasulfide is used. This is presumablybecause, since the sulfide moiety of the linking unit A is a C—S—C bond,the compound is thermally more stable than tetrasulfide or disulfide,and thus the Mooney viscosity is less likely to increase.

Moreover, the decrease in the scorch time is suppressed compared to thecase where mercapto silane such as 3-mercaptopropyltrimethoxysilane isused. This is presumably because, though the linking unit B has amercapto silane structure, the —C₇H₁₅ moiety of the linking unit Acovers a —SH group of the linking unit B, as a result of which the SHgroup is less likely to react with polymers. Thus, scorch is less likelyto occur.

From the viewpoint of enhancing the effects of suppressing the viscosityincrease during the processing and of suppressing the decrease in thescorch time as mentioned above, the linking unit A content in the silanecoupling agent having the foregoing structure is preferably not lessthan 30 mol %, and more preferably not less than 50 mol %, but ispreferably not more than 99 mol %, and more preferably not more than 90mol %. The linking unit B content is preferably not less than 1 mol %,more preferably not less than 5 mol %, and still more preferably notless than 10 mol %, but is preferably not more than 70 mol %, morepreferably not more than 65 mol %, and still more preferably not morethan 55 mol %. The combined amount of the linking unit A and the linkingunit B is preferably not less than 95 mol %, more preferably not lessthan 98 mol %, and particularly preferably 100 mol %.

The amount of the linking unit A or B is the amount including thelinking unit A or B that is present at the terminal of the silanecoupling agent, if any. In the case where the linking unit A or B ispresent at the terminal of the silane coupling agent, its form is notparticularly limited as long as it forms a unit corresponding to theformula (2) representing the linking unit A or the formula (3)representing the linking unit B.

Examples of the halogen atom for R²⁰¹ include chlorine, bromine, andfluorine.

Examples of the branched or unbranched C₁₋₃₀ alkyl group for R²⁰¹include a methyl group, an ethyl group, an n-propyl group, an isopropylgroup, an n-butyl group, an iso-butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a heptyl group, a2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group.The alkyl group preferably has 1 to 12 carbon atom(s).

Examples of the branched or unbranched O₂₋₃₀ alkenyl group for R²⁰¹include a vinyl group, a 1-propenyl group, a 2-propenyl group, a1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenylgroup, a 1-hexenyl group, a 2-hexenyl group, and a 1-octenyl group. Thealkenyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or unbranched C₂₋₃₀ alkynyl group for R²⁰¹include an ethynyl group, a propynyl group, a butynyl group, a pentynylgroup, a hexynyl group, a heptynyl group, an octynyl group, a nonynylgroup, a decynyl group, an undecynyl group, and a dodecynyl group. Thealkynyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or unbranched C₁₋₃₀ alkylene group for R²⁰²include an ethylene group, a propylene group, a butylene group, apentylene group, a hexylene group, a heptylene group, an octylene group,a nonylene group, a decylene group, an undecylene group, a dodecylenegroup, a tridecylene group, a tetradecylene group, a pentadecylenegroup, a hexadecylene group, a heptadecylene group, and an octadecylenegroup. The alkylene group preferably has 1 to 12 carbon atom(s).

Examples of the branched or unbranched C₂₋₃₀ alkenylene group for R²⁰²include a vinylene group, a 1-propenylene group, a 2-propenylene group,a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a2-pentenylene group, a 1-hexenylene group, a 2-hexenylene group, and a1-octenylene group. The alkenylene group preferably has 2 to 12 carbonatoms.

Examples of the branched or unbranched C₂₋₃₀ alkynylene group for R²⁰²include an ethynylene group, a propynylene group, a butynylene group, apentynylene group, a hexynylene group, a heptynylene group, anoctynylene group, a nonynylene group, a decynylene group, anundecynylene group, and a dodecynylene group. The alkynylene grouppreferably has 2 to 12 carbon atoms.

In the compound containing the linking unit A represented by the formula(2) and the linking unit B represented by the formula (3), the totalnumber of repetitions (x+y) of the number of repetitions (x) of thelinking unit A and the number of repetitions (y) of the linking unit Bis preferably in the range of 3 to 300. If the total number ofrepetitions is in the range mentioned above, the —C₇H₁₅ moiety of thelinking unit A covers the mercaptosilane of the linking unit B, whichenables not only to suppress the decrease in the scorch time but also tosurely achieve good reactivity to silica and the rubber component.

Examples of the compound containing the linking unit A represented bythe formula (2) and the linking unit B represented by the formula (3)include NXT-Z30, NXT-Z45, and NXT-Z60 (produced by Momentive PerformanceMaterials). Any of these may be used alone, or two or more of these maybe used in combination.

The amount of the mercapto group-containing silane coupling agent ispreferably not less than 0.5 parts by mass, and more preferably not lessthan 3 parts by mass for each 100 parts by mass of the silica. If theamount is less than 0.5 parts by mass, the resulting unvulcanized rubbercomposition tends to have high viscosity. Thus, sufficientprocessability may not be surely achieved. Also, the amount of themercapto group-containing silane coupling agent is preferably not morethan 20 parts by mass, and more preferably not more than 10 parts bymass. If the amount exceeds 20 parts by mass, the rubber strength andabrasion resistance tend to deteriorate.

The rubber composition of the present invention preferably includesother silane coupling agents as well as the mercapto group-containingsilane coupling agent. This enables to enhance the effect of improvingthe properties. Examples of other silane coupling agents includebis(3-triethoxysilylpropyl)tetrasulfide,bis(3-triethoxysilylpropyl)trisulfide,bis(3-triethoxysilylpropyl)disulfide,bis(2-triethoxysilylethyl)tetrasulfide,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,bis(3-trimethoxysilylpropyl)tetrasulfide,bis(2-trimethoxysilylethyl)tetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-trimethoxysilylpropylbenzothiazole tetrasulfide,3-triethoxysilylpropylbenzothiazolyl tetrasulfide,3-triethoxysilylpropylmethacrylate monosulfide,3-trimethoxysilylpropylmethacrylate monosulfide,bis(3-diethoxymethylsilylpropyl)tetrasulfide,3-mercaptopropyldimethoxymethylsilane,dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, anddimethoxymethylsilylpropylbenzothiazole tetrasulfide. Preferred amongthese is bis(3-triethoxysilylpropyl)tetrasulfide.

The amount of the other silane coupling agent is preferably not lessthan 0.5 parts by mass, and more preferably not less than 3 parts bymass for each 100 parts by mass of the silica. If the amount is lessthan 0.5 parts by mass, the resulting unvulcanized rubber compositionhas high viscosity. Thus, sufficient processability may not be surelyachieved. Also, the amount of the other silane coupling agent ispreferably not more than 20 parts by mass, and more preferably not morethan 10 parts by mass. If the amount exceeds 20 parts by mass, therubber strength and abrasion resistance tend to deteriorate.

The total amount of the silane coupling agents is preferably not lessthan 0.5 parts by mass, and more preferably not less than 3 parts bymass for each 100 parts by mass of the silica. If the amount is lessthan 0.5 parts by mass, the resulting unvulcanized rubber compositionhas high viscosity. Thus, sufficient processability may not be surelyachieved. Also, the total amount of the silane coupling agents ispreferably not more than 20 parts by mass, and more preferably not morethan 10 parts by mass. If the total amount exceeds 20 parts by mass, therubber strength and abrasion resistance tend to deteriorate.

The rubber composition of the present invention preferably includes asolid resin having a glass transition temperature of 60 to 120° C. Ifthe solid resin is used together with the conjugated diene polymer, theeffect of improving the properties can be synergistically enhanced.Moreover, if the solid resin is used together with the mercaptogroup-containing silane coupling agent, or the silica (1) and the silica(2), the effect of improving the properties can further be enhanced.

The solid resin has a glass transition temperature (Tg) of not lowerthan 60° C., and preferably not lower than 75° C. If the solid resin hasa glass transition temperature of lower than 60° C., the effect ofimproving the wet-grip performance may not be sufficiently achieved. Thesolid resin has a Tg of not higher than 120° C., and preferably nothigher than 100° C. If the solid resin has a Tg of higher than 120° C.,the loss elastic modulus at high temperature ranges increases greatly sothat the fuel economy tends to deteriorate.

The Tg of the solid resin is a value (midpoint glass transitiontemperature) measured at a rate of temperature rise of 10° C./min. witha differential scanning calorimeter Q200 (produced by TA InstrumentsJapan Inc.) in accordance with JIS-K7121.

Any solid resin may be used as the solid resin as long as it has a Tgmentioned above. Examples of the solid resin include an aromatic resin,such as an aromatic vinyl polymer prepared by polymerizing α-methylstyrene and/or styrene, a coumarone-indene resin, or an indene resin; aterpene resin; and a rosin resin. The derivatives of those resins mayalso be used. An aromatic resin is preferable, and an aromatic vinylpolymer prepared by polymerizing α-methyl styrene and/or styrene and acoumarone-indene resin are more preferable, as the use of such solidrubber enables to provide an unvulcanized rubber composition with goodadhesion property and to achieve good fuel economy.

Styrene and/or α-methyl styrene is used as an aromatic vinyl monomer(unit) of the aromatic vinyl polymer prepared by polymerizing α-methylstyrene and/or styrene (resin obtained by polymerizing α-methyl styreneand/or styrene). The aromatic vinyl polymer may be a homopolymer of onemonomer, or a copolymer of both monomers. Preferably, the aromatic vinylpolymer is a homopolymer of α-methyl styrene, or a copolymer of α-methylstyrene and styrene as use of such a homopolymer or copolymer is costefficient, and enables to achieve good processability and excellentwet-grip performance.

The aromatic vinyl polymer has a weight-average molecular weight (Mw) ofpreferably not less than 500, and more preferably not less than 800. Ifthe Mw is less than 500, the effect of improving the wet-gripperformance tends not to be easily achieved sufficiently. The aromaticvinyl polymer has a weight-average molecular weight of preferably notmore than 3000, and more preferably not more than 2000. If the Mw ismore than 3000, the dispersibility of the filler decreases so that thefuel economy tends to deteriorate.

Herein, the weight-average molecular weight can be measured using gelpermeation chromatography (GPC) (GPC-8000 series produced by TosohCorporation, detector: differential refractometer) and expressed as apolystyrene-equivalent value.

The coumarone-indene resin and the indene resin are a coal or petroleumresin containing coumarone having eight carbon atoms and indene havingnine carbon atoms as principal monomers, and a coal or petroleum resincontaining indene as a principal monomer, respectively. Specificexamples thereof include vinyltoluene-α-methylstyrene-indene resin,vinyltoluene-indene resin, α-methylstyrene-indene resin, andα-methylstyrene-vinyltoluene-indene copolymer resin.

The terpene resin is a resin that is derived from, as a principalmonomer, a terpene compound having a terpene backbone such as amonoterpene, a sesquiterpene or a diterpene. Examples thereof includeα-pinene resin, β-pinene resin, limonene resin, dipentene resin,β-pinene/limonene resins, aromatic modified terpene resin, terpenephenolic resin, and hydrogenated terpene resin. Examples of the rosinresin include natural rosin resin (polymerized rosin) such as gum rosin,wood rosin and tall oil rosin, hydrogenated rosin resins, maleicacid-modified rosin resin, rosin-modified phenolic resin, rosin glycerolesters, and disproportionated rosin resin. Natural rosin resins can beproduced by processing pine resin, and each mainly contains a resin acidsuch as abietic acid or pimaric acid.

The amount of the solid resin is preferably not less than 1 part bymass, more preferably not less than 3 parts by mass, and still morepreferably not less than 5 parts by mass for each 100 parts by mass ofthe rubber component. If the amount is less than 1 part by mass, theeffect of improving the wet-grip performance tends not to besufficiently achieved. The amount of the solid resin is preferably notmore than 30 parts by mass, and more preferably not more than 15 partsby mass. If the amount is more than 30 parts by mass, the elasticmodulus of the rubber composition at low temperature ranges increasesgreatly. Thus, the grip performance on snowy roads and the wet-gripperformance in cold regions tend to deteriorate.

The rubber composition of the present invention preferably includes atleast one liquid resin having a glass transition temperature of −40 to20° C. selected from the group consisting of aromatic petroleum resins,terpene resins, and rosin resins, and/or a plasticizer having a glasstransition temperature of −40 to 20° C. The rubber composition morepreferably includes the solid resin as well as the liquid resin and/orthe plasticizer. This enables not only to improve the grip performancein wide temperature ranges but also to improve the rubber strength whilemaintaining the fuel economy.

The liquid resin and the plasticizer each have a Tg of not lower than−40° C., and preferably not lower than −20° C. A Tg of lower than −40°C. excessively increases the action of plasticizing rubber so that theabrasion resistance tends to deteriorate. The liquid resin and theplasticizer each have a Tg of not higher than 20° C., and preferably nothigher than 10° C. A Tg of higher than 20° C. leads to a large losselastic modulus so that the fuel economy tends to deteriorate.

The Tg of the liquid resin and that of the plasticizer are values(midpoint glass transition temperatures) measured at a rate oftemperature rise of 10° C./min. with a differential scanning calorimeterQ200 (produced by TA Instruments Japan Inc.) in accordance withJIS-K7121.

The liquid resin to be used is at least one selected form the groupconsisting of aromatic petroleum resins, terpene resins, and rosinresins. An aromatic petroleum resin is preferable as it has a highereffect of improving the rubber strength.

The aromatic petroleum resin applicable as the liquid resin is a resinobtained by polymerizing an aromatic fraction having 9 carbon atoms (C9)containing, as a principal monomer, vinyl toluene or indene which isusually produced by thermal decomposition of naphtha. Examples thereofinclude low molecular weight forms listed for the solid resin, such asan aromatic vinyl polymer prepared by polymerizing α-methyl styreneand/or styrene, a coumarone resin, or a coumarone-indene resin.Preferred among these are a homopolymer of α-methyl styrene, a copolymerof α-methyl styrene and styrene, a coumarone resin, and acoumarone-indene resin, and more preferred is a coumarone-indene resin,as these resins have a higher effect of improving the rubber strength,abrasion resistance, and wet-grip performance.

Examples of commercially available products of such resins includeNOVARES C10 (produced by Rutgers chemicals AG), and Picco A-10 (producedby Eastoman Chemical Company).

Low molecular weight forms of the terpene resins and the rosin resinslisted for the solid resin may be used as the liquid resin. Examples ofcommercially available products of the terpene resin that can be used asthe liquid resin include YS resin PX300, YS resin PX300N, Dimerone, andYS Polyster T30 (produced by Yasuhara Chemical Co., Ltd.). Examples ofcommercially available products of the rosin resin that can be used asthe liquid resin include HARIESTER SK-501NS (produced by HarimaChemicals, Inc.).

Any plasticizer may be used as the plasticizer as long as it has a Tgmentioned above. Examples of the plasticizer include a diene polymerhaving a weight average molecular weight (Mw) of 3,000 to 150,000. Inthe case of using a diene polymer as the plasticizer, a diene polymerhaving an epoxidation degree of not more than 25 mol % is preferablyused.

The combined amount of the liquid resin and the plasticizer ispreferably not less than 1 part by mass, and more preferably not lessthan 5 parts by mass for each 100 parts by mass of the rubber component.If the combined amount is less than 1 part by mass, the rubber strengthand the grip performance in wide temperature ranges may not besufficiently improved. The combined amount is preferably not more than30 parts by mass, more preferably not more than 20 parts by mass, andstill more preferably not more than 10 parts by mass. If the combinedamount is more than 30 parts by mass, the rigidity of the rubbercomposition tends to be greatly impaired, and the handling stabilitytend to decrease.

The combined amount of the solid resin, the liquid resin and theplasticizer for each 100 parts by mass of the rubber component ispreferably not less than 2 parts by mass, and more preferably not lessthan 6 parts by mass, but is preferably not more than 60 parts by mass,more preferably not more than 30 parts by mass, and still morepreferably not more than 20 parts by mass. If the combined amount iswithin the range mentioned above, balanced improvements inprocessability, fuel economy, rubber strength, abrasion resistance,wet-grip performance, and handling stability can be achieved at highlevels.

Known additives may be used, and examples thereof include vulcanizationagents such as sulfur; vulcanization accelerators such as athiazole-based vulcanization accelerator, a thiuram-based vulcanizationaccelerator, a sulfenamide-based vulcanization accelerator, and aguanidine-based vulcanization accelerator; vulcanization activatingagents such as stearic acid and zinc oxide; organic peroxides; fillerssuch as carbon black, calcium carbonate, talc, alumina, clay, aluminumhydroxide, and mica; processing aids such as extender oils andlubricants; and antioxidants.

Examples of the carbon black include furnace black (furnace carbonblack) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF orECF; acetylene black (acetylene carbon black); thermal black (thermalcarbon black) such as FT or MT; channel black (channel carbon black)such as EPC, MPC or CC; and graphite. Any of these may be used alone ortwo or more of these may be used in combination.

The amount of carbon black is preferably not less than 1 part by mass,and more preferably not less than 3 parts by mass for each 100 parts bymass of the rubber component. If the amount is less than 1 part by mass,sufficient reinforcement may not be achieved. Also, the amount of carbonblack is preferably not more than 60 parts by mass, more preferably notmore than 30 parts by mass, and still more preferably not more than 15parts by mass. If the amount is more than 60 parts by mass, the fueleconomy tends to deteriorate.

The nitrogen adsorption specific surface area (N₂SA) of carbon black isusually 5 to 200 m²/g, and preferably the lower limit and the upperlimit thereof are 50 m²/g and 150 m²/g, respectively. The dibutylphthalate (DBP) absorption of carbon black is usually 5 to 300 mL/100 g,and preferably the lower limit and the upper limit thereof are 80 mL/100g and 180 mL/100 g, respectively. If the N₂SA or DBP absorption ofcarbon black is lower than the lower limit of the range mentioned above,the reinforcement is small, and the abrasion resistance tends todecrease. If the N₂SA or DBP absorption of carbon black is larger thanthe upper limit of the range mentioned above, the carbon black does notdisperse well, and the hysteresis loss increases. Thus, the fuel economytends to deteriorate. The nitrogen adsorption specific surface area ismeasured in accordance with ASTM D4820-93. The DBP absorption ismeasured in accordance with ASTM D2414-93. Examples of commerciallyavailable carbon black include SEAST 6, SEAST 7HM, and SEAST KH (tradename, produced by Tokai Carbon Co., Ltd.), and CK 3 and Special Black 4A(trade name, produced by Evonik Degussa).

Examples of the extender oil include aromatic mineral oils (viscositygravity constant (V.G.C. value) 0.900 to 1.049), naphthenic mineral oils(V.G.C. value 0.850 to 0.899), and paraffinic mineral oils (V.G.C. value0.790 to 0.849). The polycyclic aromatic content in the extender oil ispreferably less than 3% by mass, and more preferably less than 1% bymass. The polycyclic aromatic content is measured according to theBritish Institute of Petroleum 346/92 Method. The aromatic compound (CA)content in the extender oil is preferably not less than 20% by mass ormore. Two or more kinds of these extender oils may be used incombination.

Examples of the vulcanization accelerator include thiazole-basedvulcanization accelerators such as 2-mercaptobenzothiazole,dibenzothiazyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide;thiuram-based vulcanization accelerators such as tetramethylthiurammonosulfide and tetramethylthiuram disulfide; sulfenamide-basedvulcanization accelerators such asN-cyclohexyl-2-benzothiazolesulfenamide,N-t-butyl-2-benzothiazolesulfenamide,N-oxyethylene-2-benzothiazolesulfenamide,N-oxyethylene-2-benzothiazolesulfenamide, andN,N′-diisopropyl-2-benzothiazolesulfenamide; and guanidine-basedvulcanization accelerators such as diphenylguanidine,diorthotolylguanidine, and orthotolylbiguanidine. The amount thereof tobe used is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to3 parts by mass for each 100 parts by mass of the rubber component.

Known methods may be employed for producing a rubber composition byadding other rubber materials and additives to the conjugated dienepolymer. Examples of the method include a method of kneading componentswith a known mixer such as a roll mill or a Banbury mixer.

With regard to the kneading conditions for the case where additivesother than the vulcanization agent and the vulcanization accelerator aremixed, the kneading temperature is usually 50 to 200° C., and preferably80 to 190° C., and the kneading time is usually 30 seconds to 30minutes, and preferably 1 minute to 30 minutes.

In the case where the vulcanization agent and the vulcanizationaccelerator are mixed, the kneading temperature is usually not higherthan 100° C., and preferably room temperature to 80° C. The compositioncontaining a vulcanization agent and a vulcanization accelerator isusually used after it is vulcanized by press vulcanization or the like.The vulcanization temperature is usually 120 to 200° C., and preferably140 to 180° C.

The rubber composition of the present invention has a tan δ peaktemperature of preferably not lower than −16° C. The rubber compositionhaving a tan δ peak temperature of lower than −16° C. may fail to exertsufficient wet-grip performance required for summer tires. The rubbercomposition of the present invention has a tan δ peak temperature ofpreferably not higher than −5° C., and more preferably not higher than−8° C. The rubber composition having a tan δ peak temperature of higherthan −5° C. has high temperature dependence, and thus tends not to exertsufficient wet-grip performance in wide temperature ranges.

The tan δ peak temperature is measured by the method described inexamples below.

The rubber composition of the present invention is excellent in thebalance among processability, fuel economy, rubber strength, abrasionresistance, wet-grip performance, and handling stability, and haseffects of significantly improving these properties.

The rubber composition of the present invention may be used in acomponent of a tire, suitably in a tread (particularly a tread of summertires).

The pneumatic tire of the present invention is formed from the rubbercomposition by a usual method. Namely, before vulcanization, the rubbercomposition optionally containing various additives is extruded andprocessed into the shape of a tire component (e.g., tread), and thenmolded in a normal manner on a tire building machine and assembled withother tire components to provide an unvulcanized tire. Then, theunvulcanized tire is heated and pressed in a vulcanizer into a pneumatictire. Thus, the pneumatic tire of the present invention can be produced.

The pneumatic tire of the present invention can be suitably used assummer tires (particularly, summer tires for passenger vehicles).

EXAMPLES

The present invention is more specifically described based on examples.However, the present invention is not limited thereto.

The following is a list of chemical agents used in the synthesis orpolymerization. The chemical agents were purified as needed by usualmethods.

THF: anhydrous tetrahydrofuran, produced by Kanto Chemical Co., Inc.

Sodium hydride: produced by Kanto Chemical Co., Inc.

Diethylamine: produced by Kanto Chemical Co., Inc.

Methylvinyldichlorosilane: produced by Shin-Etsu Chemical Co., Ltd.

Anhydrous hexane: produced by Kanto Chemical Co., Inc.

Styrene: produced by Kanto Chemical Co., Inc.

Butadiene: 1,3-butadiene, produced by Tokyo Chemical Industry Co., Ltd.

TMEDA: tetramethylethylenediamine, produced by Kanto Chemical Co., Inc.

n-Butyllithium solution: 1.6 M n-butyllithium in hexane, produced byKanto Chemical Co., Inc.

Initiator (1): AI-200CE2 (compound prepared by bonding3-(N,N-dimethylamino)-1-propyllithium and two isoprene-derivedstructural units, represented by the following formula) (0.9 M),produced by FMC

Piperidine: produced by Tokyo Chemical Industry Co., Ltd.Diamylamine: produced by Tokyo Chemical Industry Co., Ltd.2,6-Di-tert-butyl-p-cresol: Nocrac 200, produced by Ouchi ShinkoChemical Industrial Co., Ltd.Bis(dimethylamino)methylvinylsilane: produced by Shin-Etsu Chemical Co.,Ltd.N,N-dimethylaminopropylacrylamide: produced by Tokyo Chemical IndustryCo., Ltd.3-Diethylaminopropyltriethoxysilane: produced by Azmax Co., Ltd.1,3-Dimethyl-2-imidazolidinone: produced by Tokyo Chemical Industry Co.,Ltd.N-phenyl-2-pyrrolidone: produced by Tokyo Chemical Industry Co., Ltd.N-methyl-ε-caprolactam: produced by Tokyo Chemical Industry Co., Ltd.Tris[3-(trimethoxysilyl)propyl]isocyanurate: produced by Shin-EtsuChemical Co., Ltd.N,N-dimethylformamide dimethyl acetal: produced by Tokyo ChemicalIndustry Co., Ltd.1,3-Diisopropenylbenzene: produced by Tokyo Chemical Industry Co., Ltd.sec-Butyllithium solution: produced by Kanto Chemical Co., Inc. (1.0mol/L)Cyclohexane: produced by Kanto Chemical Co., Inc.<Production of Modifier (1) (Main Chain Modifier)>

In a nitrogen atmosphere, 15.8 g of bis(dimethylamino)methylvinylsilanewas charged into a 100-mL volumetric flask, and also anhydrous hexanewas added to increase the total amount to 100 mL. In this manner, amodifier (1) was produced.

<Production of Modifier (2) (Terminal Modifier)>

In a nitrogen atmosphere, 15.6 g of N,N-dimethylaminopropylacrylamidewas charged into a 100-mL volumetric flask, and also anhydrous hexanewas added to increase the total amount to 100 mL. In this manner, amodifier (2) was produced.

<Production of Modifier (3) (Main Chain Modifier)>

THF (1000 mL) and sodium hydride (13 g) were charged into a sufficientlynitrogen-purged 2-L three-necked flask, and diethylamine (36.5 g) wasslowly added dropwise thereto on an ice water bath while stirring. Afterstirring for 30 minutes, methylvinyldichlorosilane (36 g) was addeddropwise over 30 minutes, followed by stirring for 2 hours. Theresulting solution was concentrated, filtered, and purified bydistillation under reduced pressure to givebis(diethylamino)methylvinylsilane. Thebis(diethylamino)methylvinylsilane (21.4 g) was charged into a 100-mLvolumetric flask in a nitrogen atmosphere, and also anhydrous hexane wasadded to increase the total amount to 100 mL. In this manner, a modifier(3) was produced.

<Production of Initiator (2)>

Anhydrous hexane (127.6 mL) and piperidine (8.5 g) were charged into asufficiently nitrogen-purged 200-mL recovery flask, and cooled to 0° C.Then, an n-butyllithium solution (62.5 mL) was slowly added over 1 hourto give an initiator (2).

<Production of Initiator (3)>

Anhydrous hexane (117 mL) and diamylamine (15.7 g) were charged into asufficiently nitrogen-purged 200-mL recovery flask, and cooled to 0° C.Then, an n-butyllithium solution (62.5 mL) was slowly added over 1 hourto give an initiator (3).

<Production of Modifier (4) (Terminal Modifier)>

In a nitrogen atmosphere, 3-diethylaminopropyltriethoxysilane (27.7 g)was charged into a 100-mL volumetric flask, and also anhydrous hexanewas added to increase the total amount to 100 mL. In this manner, amodifier (4) was produced.

<Production of Initiator (4) (Bifunctional Initiator)>

Cyclohexane (550 mL), TMEDA (27 mL), and a sec-butyllithium solution(200 mL) were charged into a sufficiently dried and nitrogen-purged 1-Lrecovery flask. While the mixture was stirred at 45° C.,1,3-diisopropenylbenzene (17 mL) was slowly added thereto over 30minutes. The resulting mixed solution was stirred for another 1 hour,and then cooled to room temperature to give an initiator (4).

<Production of Modifier (5) (Terminal Modifier)>

In a nitrogen atmosphere, 1,3-dimethyl-2-imidazolidinone (11.4 g) wascharged into a 100-mL volumetric flask, and also anhydrous hexane wasadded to increase the total amount to 100 mL. In this manner, a modifier(5) was produced.

<Production of Modifier (6) (Terminal Modifier)>

In a nitrogen atmosphere, N-phenyl-2-pyrrolidone (16.1 g) was chargedinto a 100-mL volumetric flask, and also anhydrous hexane was added toincrease the total amount to 100 mL. In this manner, a modifier (6) wasproduced.

<Production of Modifier (7) (Terminal Modifier)>

In a nitrogen atmosphere, N-methyl-ε-caprolactam (12.7 g) was chargedinto a 100-mL volumetric flask, and also anhydrous hexane was added toincrease the total amount to 100 mL. In this manner, a modifier (7) wasproduced.

<Production of Modifier (8) (Terminal Modifier)>

In a nitrogen atmosphere, tris[3-(trimethoxysilyl)propyl]isocyanurate(30.7 g) was charged into a 100-mL volumetric flask, and also anhydroushexane was added to increase the total amount to 200 mL. In this manner,a modifier (8) was produced.

<Production of Modifier (9) (Terminal Modifier)>

In a nitrogen atmosphere, N,N-dimethylformamide dimethyl acetal (11.9 g)was charged into a 100-mL volumetric flask, and also anhydrous hexanewas added to increase the total amount to 200 mL. In this manner, amodifier (9) was produced.

<Copolymer Analysis>

Copolymers (conjugated diene polymers) obtained as mentioned later wereanalyzed by the following methods.

<Measurement of Weight-Average Molecular Weight (Mw) and Number-AverageMolecular Weight (Mn)>

The weight-average molecular weight (Mw) and number-average molecularweight (Mn) of each copolymer were measured using gel permeationchromatography (GPC) (GPC-8000 series produced by Tosoh Corporation,detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-Mproduced by Tosoh Corporation), and expressed relative to polystyrenestandards. A molecular weight distribution Mw/Mn was calculated from themeasurement results.

<Structural Identification of Copolymers>

Structures (styrene content, vinyl content) of copolymers wereidentified with a device of JNM-ECA series produced by JEOL Ltd. Eachpolymer (0.1 g) was dissolved in toluene (15 mL), and the solution wasslowly introduced in methanol (30 mL) for reprecipitation. The resultingprecipitate was dried under reduced pressure, and then measured.

<Synthesis of Copolymer (1)>

n-Hexane (18 L), styrene (600 g), butadiene (1400 g), the modifier (1)(40 mL), and TMEDA (10 mmol) were charged into a sufficientlynitrogen-purged 30-L pressure resistant container, and heated to 40° C.After further addition of the initiator (2) (34 mL), the mixture washeated to 50° C., and stirred for 3 hours. Next, the modifier (2) (20mL) was added, followed by stirring for 30 minutes, and the reactionsolution was mixed with methanol (15 mL) and 2,6-tert-butyl-p-cresol(0.1 g). Thereafter, a coagulum was recovered from the polymer solutionby steam stripping treatment, and the coagulum was dried under reducedpressure for 24 hours to give a copolymer (1). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (2)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (2)>

A copolymer (2) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the initiator (3) (34 mL)was used instead of the initiator (2) (34 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (3)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (2)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (3)>

A copolymer (3) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the amounts of styrene andbutadiene were changed to 900 g and 1100 g, respectively. Here, 0.32 gof the silicon-containing vinyl compound (modifier (1)) was added foreach 100 g of the monomer component; 0.85 mmol of the polymerizationinitiator (initiator (2)) was added for each 100 g of the monomercomponent; and 1.18 mol of the compound (modifier (2)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (4)>

A copolymer (4) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the initiator (1) (19 mL)was used instead of the initiator (2) (34 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (2)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (5)>

n-Hexane (18 L), styrene (600 g), butadiene (1400 g), the modifier (1)(75 mL), and TMEDA (10 mmol) were charged into a sufficientlynitrogen-purged 30-L pressure resistant container, and heated to 40° C.After further addition of the initiator (1) (19 mL), the mixture washeated to 50° C. and stirred for 30 minutes. Further, the modifier (1)(75 mL) was added, and the mixture was stirred for 2.5 hours. Next, themodifier (2) (20 mL) was added, followed by stirring for 30 minutes, andthe reaction solution was mixed with methanol (1 mL) and2,6-tert-butyl-p-cresol (0.1 g). Thereafter, a coagulum was recoveredfrom the polymer solution by steam stripping treatment, and the coagulumwas dried under reduced pressure for 24 hours to give a copolymer (5).Here, 1.19 g of the silicon-containing vinyl compound (modifier (1)) wasadded for each 100 g of the monomer component; 0.85 mmol of thepolymerization initiator (initiator (1)) was added for each 100 g of themonomer component; and 1.18 mol of the compound (modifier (2))containing a nitrogen atom and/or a silicon atom was added per mol ofthe alkali metal derived from the polymerization initiator added.

<Synthesis of Copolymer (6)>

A copolymer (6) was produced based on the same formulation as that forsynthesis of the copolymer (4), except that the amounts of styrene andbutadiene were changed to 0 g and 2000 g, respectively; THF (5 mmol) wasused instead of TMEDA (10 mmol); and the initiator (1) (23 mL) was usedinstead of the initiator (1) (19 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 1.05 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and0.95 mol of the compound (modifier (2)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (7)>

A copolymer (7) was produced based on the same formulation as that forsynthesis of the copolymer (4), except that the modifier (3) (40 mL) wasused instead of the modifier (1) (40 mL). Here, 0.43 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (2)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (8)>

A copolymer (8) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that an n-butyllithium solution(10.6 mL) was used instead of the initiator (1) (19 mL). Here, 0.43 g ofthe silicon-containing vinyl compound (modifier (3)) was added for each100 g of the monomer component; and 1.18 mol of the compound (modifier(2)) containing a nitrogen atom and/or a silicon atom was added per molof the alkali metal derived from the polymerization initiator added.

<Synthesis of Copolymer (9)>

A copolymer (9) was produced based on the same formulation as that forsynthesis of the copolymer (6), except that an n-butyllithium solution(13 mL) was used instead of the initiator (1) (23 mL). Here, 0.43 g ofthe silicon-containing vinyl compound (modifier (1)) was added for each100 g of the monomer component; and 0.95 mol of the compound (modifier(2)) containing a nitrogen atom and/or a silicon atom was added per molof the alkali metal derived from the polymerization initiator added.

<Synthesis of Copolymer (10)>

A copolymer (10) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the amount of the modifier(1) was changed from 40 mL to 0 mL. Here, 0.85 mmol of thepolymerization initiator (initiator (2)) was added for each 100 g of themonomer component; and 1.18 mol of the compound (modifier (2))containing a nitrogen atom and/or a silicon atom was added per mol ofthe alkali metal derived from the polymerization initiator added.

<Synthesis of Copolymer (11)>

A copolymer (11) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the amount of the modifier(2) was changed from 20 mL to 0 mL. Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; and 0.85 mmol of the polymerizationinitiator (initiator (2)) was added for each 100 g of the monomercomponent.

<Synthesis of Copolymer (12)>

n-Hexane (18 L), styrene (600 g), butadiene (1400 g), and TMEDA (10mmol) were charged into a sufficiently nitrogen-purged 30-L pressureresistant container, and heated to 40° C. After further addition of ann-butyllithium solution (11 mL), the mixture was heated to 50° C. andstirred for 3 hours. Next, the reaction solution was mixed with methanol(1 mL) and 2,6-tert-butyl-p-cresol (0.1 g). A coagulum was recoveredfrom the polymer solution by steam stripping treatment, and the coagulumwas dried under reduced pressure for 24 hours to give a copolymer (12).

<Synthesis of Copolymer (13)>

A copolymer (13) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that a coagulum was recoveredfrom the polymer solution not by steam stripping treatment but byevaporating the polymer solution at room temperatures for 24 hours,followed by drying the coagulum under reduced pressure. Here, 0.43 g ofthe silicon-containing vinyl compound (modifier (3)) was added for each100 g of the monomer component; 0.85 mmol of the polymerizationinitiator (initiator (1)) was added for each 100 g of the monomercomponent; and 1.18 mol of the compound (modifier (2)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (14)>

A copolymer (14) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the amounts of the modifier(3) (40 mL) and the modifier (2) (20 mL) were changed to 0 mL. Here, 8.5mmol of the polymerization initiator (initiator (1)) was added for each100 g of the monomer component.

<Synthesis of Copolymer (15)>

A copolymer (15) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that an n-butyllithium solution(6.8 mL) was used instead of the initiator (1) (19 mL), and the amountof the modifier (2) was changed from 20 mL to 0 mL. Here, 0.43 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component.

<Synthesis of Copolymer (16)>

A copolymer (16) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that an n-butyllithium solution(6.8 mL) was used instead of the initiator (1) (19 mL); and the amountof the modifier (3) was changed from 40 mL to 0 mL. Here, 1.18 mol ofthe compound (modifier (2)) containing a nitrogen atom and/or a siliconatom was added per mol of the alkali metal derived from thepolymerization initiator added.

<Synthesis of Copolymer (17)>

A copolymer (17) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the initiator (4)(bifunctional initiator, 68 mL) was used instead of the initiator (2)(34 mL); and the amount of the modifier (2) was changed from 20 mL to 40mL. Here, 0.32 g of the silicon-containing vinyl compound (modifier (1))was added for each 100 g of the monomer component; and 2.28 mol (1.14mol for each terminal) of the compound (modifier (2)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (18)>

A copolymer (18) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the amounts of styrene andbutadiene were changed to 0 g and 2000 g, respectively; THF (5 mmol) wasused instead of TMEDA (10 mmol); and the amount of the initiator (1) waschanged from 19 mL to 23 mL). Here, 0.43 g of the silicon-containingvinyl compound (modifier (3)) was added for each 100 g of the monomercomponent; 0.85 mmol of the polymerization initiator (initiator (1)) wasadded for each 100 g of the monomer component; and 1.18 mol of thecompound (modifier (2)) containing a nitrogen atom and/or a silicon atomwas added per mol of the alkali metal derived from the polymerizationinitiator added.

<Synthesis of Copolymer (19)>

A copolymer (19) was produced based on the same formulation as that forsynthesis of the copolymer (8), except that the amounts of styrene andbutadiene were changed to 0 g and 2000 g, respectively; and THF (5 mmol)was used instead of TMEDA (10 mmol). Here, 0.43 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; and 1.18 mol of the compound (modifier (2))containing a nitrogen atom and/or a silicon atom was added per mol ofthe alkali metal derived from the polymerization initiator added.

<Synthesis of Copolymer (20)>

n-Hexane (18 L), butadiene (2000 g), and THF (5 mmol) were charged intoa sufficiently nitrogen-purged 30-L pressure resistant container, andheated to 40° C. After further addition of an n-butyllithium solution(11 mL), the mixture was heated to 50° C., and stirred for 3 hours.Next, the reaction solution was mixed with methanol (1 mL) and2,6-tert-butyl-p-cresol (0.1 g). Then, a coagulum was recovered from thepolymer solution by steam stripping treatment, and the coagulum wasdried under reduced pressure for 24 hours to give a copolymer (20).

<Synthesis of Copolymer (21)>

A copolymer (21) was produced based on the same formulation as that forsynthesis of the copolymer (18), except that a coagulum was recoveredfrom the polymer solution not by steam stripping treatment but byevaporating the polymer solution at room temperatures for 24 hours,followed by drying the coagulum under reduced pressure. Here, 0.43 g ofthe silicon-containing vinyl compound (modifier (3)) was added for each100 g of the monomer component; 0.85 mmol of the polymerizationinitiator (initiator (1)) was added for each 100 g of the monomercomponent; and 1.18 mol of the compound (modifier (2)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (22)>

A copolymer (22) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (23)>

A copolymer (23) was produced based on the same formulation as that forsynthesis of the copolymer (2), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (3)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (24)>

A copolymer (24) was produced based on the same formulation as that forsynthesis of the copolymer (3), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (25)>

A copolymer (25) was produced based on the same formulation as that forsynthesis of the copolymer (4), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (26)>

A copolymer (26) was produced based on the same formulation as that forsynthesis of the copolymer (5), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 1.19 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (27)>

A copolymer (27) was produced based on the same formulation as that forsynthesis of the copolymer (6), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 1.05 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and0.95 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (28)>

A copolymer (28) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the modifier (4) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (29)>

A copolymer (29) was produced based on the same formulation as that forsynthesis of the copolymer (28), except that a coagulum was recoveredfrom the polymer solution not by steam stripping treatment but byevaporating the polymer solution at room temperatures for 24 hours,followed by drying the coagulum under reduced pressure. Here, 0.32 g ofthe silicon-containing vinyl compound (modifier (3)) was added for each100 g of the monomer component; 0.85 mmol of the polymerizationinitiator (initiator (1)) was added for each 100 g of the monomercomponent; and 1.18 mol of the compound (modifier (4)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (30)>

A copolymer (30) was produced based on the same formulation as that forsynthesis of the copolymer (28), except that an n-butyllithium solution(10.6 mL) was used instead of the initiator (1) (19 mL); and the amountof the modifier (3) was changed from 40 mL to 0 mL. Here, 1.18 mol ofthe compound (modifier (4)) containing a nitrogen atom and/or a siliconatom was added per mol of the alkali metal derived from thepolymerization initiator added.

<Synthesis of Copolymer (31)>

A copolymer (31) was produced based on the same formulation as that forsynthesis of the copolymer (18), except that the modifier (4) (20 mL)was used instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (4)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (32)>

A copolymer (32) was produced based on the same formulation as that forsynthesis of the copolymer (31), except that a coagulum was recoveredfrom the polymer solution not by steam stripping treatment but byevaporating the polymer solution at room temperatures for 24 hours,followed by drying the coagulum under reduced pressure. Here, 0.32 g ofthe silicon-containing vinyl compound (modifier (3)) was added for each100 g of the monomer component; 0.85 mmol of the polymerizationinitiator (initiator (1)) was added for each 100 g of the monomercomponent; and 1.18 mol of the compound (modifier (4)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (33)>

A copolymer (33) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the modifier (5) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (5)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (34)>

A copolymer (34) was produced based on the same formulation as that forsynthesis of the copolymer (2), except that the modifier (5) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (3)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (5)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (35)>

A copolymer (35) was produced based on the same formulation as that forsynthesis of the copolymer (3), except that the modifier (5) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (5)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (36)>

A copolymer (36) was produced based on the same formulation as that forsynthesis of the copolymer (4), except that the modifier (5) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (5)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (37)>

A copolymer (37) was produced based on the same formulation as that forsynthesis of the copolymer (5), except that the modifier (5) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 1.19 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (5)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (38)>

A copolymer (38) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the modifier (5) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (5)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (39)>

A copolymer (39) was produced based on the same formulation as that forsynthesis of the copolymer (38), except that a coagulum was recoveredfrom the polymer solution not by steam stripping treatment but byevaporating the polymer solution at room temperatures for 24 hours,followed by drying the coagulum under reduced pressure. Here, 0.32 g ofthe silicon-containing vinyl compound (modifier (3)) was added for each100 g of the monomer component; 0.85 mmol of the polymerizationinitiator (initiator (1)) was added for each 100 g of the monomercomponent; and 1.18 mol of the compound (modifier (5)) containing anitrogen atom and/or a silicon atom was added per mol of the alkalimetal derived from the polymerization initiator added.

<Synthesis of Copolymer (40)>

A copolymer (40) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the modifier (6) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (6)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (41)>

A copolymer (41) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the modifier (7) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (7)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (42)>

A copolymer (42) was produced based on the same formulation as that forsynthesis of the copolymer (38), except that a butyllithium solution(10.6 mL) was used instead of the initiator (1) (19 mL), and the amountof the modifier (3) was changed from 40 mL to 0 mL. Here, 1.18 mol ofthe compound (modifier (5)) containing a nitrogen atom and/or a siliconatom was added per mol of the alkali metal derived from thepolymerization initiator added.

<Synthesis of Copolymer (43)>

A copolymer (43) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the modifier (8) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (8)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (44)>

A copolymer (44) was produced based on the same formulation as that forsynthesis of the copolymer (2), except that the modifier (8) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (3)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (8)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (45)>

A copolymer (45) was produced based on the same formulation as that forsynthesis of the copolymer (3), except that the modifier (8) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (8)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (46)>

A copolymer (46) was produced based on the same formulation as that forsynthesis of the copolymer (4), except that the modifier (8) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (8)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (47)>

A copolymer (47) was produced based on the same formulation as that forsynthesis of the copolymer (5), except that the modifier (8) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 1.19 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (8)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (48)>

A copolymer (48) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the modifier (8) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (8)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (49)>

A copolymer (49) was produced based on the same formulation as that forsynthesis of the copolymer (48), except that a butyllithium solution(10.6 mL) was used instead of the initiator (1) (19 mL), and the amountof the modifier (3) was changed from 40 mL to 0 mL. Here, 1.18 mol ofthe compound (modifier (8)) containing a nitrogen atom and/or a siliconatom was added per mol of the alkali metal derived from thepolymerization initiator added.

<Synthesis of Copolymer (50)>

A copolymer (50) was produced based on the same formulation as that forsynthesis of the copolymer (1), except that the modifier (9) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (9)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (51)>

A copolymer (51) was produced based on the same formulation as that forsynthesis of the copolymer (2), except that the modifier (9) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (3)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (9)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (52)>

A copolymer (52) was produced based on the same formulation as that forsynthesis of the copolymer (3), except that the modifier (9) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (2)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (9)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (53)>

A copolymer (53) was produced based on the same formulation as that forsynthesis of the copolymer (4), except that the modifier (9) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (9)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (54)>

A copolymer (54) was produced based on the same formulation as that forsynthesis of the copolymer (5), except that the modifier (9) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 1.19 g of thesilicon-containing vinyl compound (modifier (1)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (9)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (55)>

A copolymer (55) was produced based on the same formulation as that forsynthesis of the copolymer (7), except that the modifier (9) (20 mL) wasused instead of the modifier (2) (20 mL). Here, 0.32 g of thesilicon-containing vinyl compound (modifier (3)) was added for each 100g of the monomer component; 0.85 mmol of the polymerization initiator(initiator (1)) was added for each 100 g of the monomer component; and1.18 mol of the compound (modifier (9)) containing a nitrogen atomand/or a silicon atom was added per mol of the alkali metal derived fromthe polymerization initiator added.

<Synthesis of Copolymer (56)>

A copolymer (56) was produced based on the same formulation as that forsynthesis of the copolymer (55), except that a butyllithium solution(10.6 mL) was used instead of the initiator (1) (19 mL), and the amountof the modifier (3) was changed from 40 mL to 0 mL. Here, 1.18 mol ofthe compound (modifier (9)) containing a nitrogen atom and/or a siliconatom was added per mol of the alkali metal derived from thepolymerization initiator added.

Tables 1 to 5 summarize the monomer components and others of thecopolymers (1) to (56).

TABLE 1 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Molecular Molecular Styrene Vinyl weightweight Terminal content content distribution Mw (unit: CopolymerInitiator Monomer component modifier (% by mass) (mol %) Mw/Mn tenthousand) Copolymer (1)  Initiator (2) Styrene, 1,3-Butadiene, Modifier(1) Modifier (2) 30 56 1.21 26.5 Copolymer (2)  Initiator (3) Styrene,1,3-Butadiene, Modifier (1) Modifier (2) 30 57 1.23 26.8 Copolymer (3) Initiator (2) Styrene, 1,3-Butadiene, Modifier (1) Modifier (2) 45 561.23 26.9 Copolymer (4)  Initiator (1) Styrene, 1,3-Butadiene, Modifier(1) Modifier (2) 30 56 1.13 24.8 Copolymer (5)  Initiator (1) Styrene,1,3-Butadiene, Modifier (1) Modifier (2) 30 56 1.20 27.1 Copolymer (6) Initiator (1) 1,3-Butadiene, Modifier (1) Modifier (2) 0 14.2 1.17 28.9Copolymer (7)  Initiator (1) Styrene, 1,3-Butadiene, Modifier (3)Modifier (2) 30 56 1.18 26.0 Copolymer (8)  n-Butyllithium solutionStyrene, 1,3-Butadiene, Modifier (3) Modifier (2) 30 55 1.17 24.5Copolymer (9)  n-Butyllithium solution 1,3-Butadiene, Modifier (1)Modifier (2) 0 13.5 1.16 29.3 Copolymer (10) Initiator (2) Styrene,1,3-Butadiene Modifier (2) 30 56 1.19 25.0 Copolymer (11) Initiator (2)Styrene, 1,3-Butadiene, Modifier (1) Not added 30 56 1.25 25.4 Copolymer(12) n-Butyllithium solution Styrene, 1,3-Butadiene Not added 30 56 1.0926.5 Copolymer (13) Initiator (1) Styrene, 1,3-Butadiene, Modifier (3)Modifier (2) 30 57 1.19 25.2 Copolymer (14) Initiator (1) Styrene,1,3-Butadiene Not added 30 57 1.16 26.1 Copolymer (15) n-Butyllithiumsolution Styrene, 1,3-Butadiene, Modifier (3) Not added 30 56 1.13 27.9Copolymer (16) n-Butyllithium solution Styrene, 1,3-Butadiene Modifier(2) 30 55 1.10 27.4 Copolymer (17) Initiator (4) Styrene, 1,3-Butadiene,Modifier (1) Modifier (2) 30 55 1.29 28.9 Copolymer (18) Initiator (1)1,3-Butadiene, Modifier (3) Modifier (2) 0 14.2 1.19 26.2 Copolymer (19)n-Butyllithium solution 1,3-Butadiene, Modifier (3) Modifier (2) 0 13.71.16 25.2 Copolymer (20) n-Butyllithium solution 1,3-Butadiene Not added0 13.9 1.11 27.1 Copolymer (21) Initiator (1) 1,3-Butadiene, Modifier(3) Modifier (2) 0 14 1.21 26.3

TABLE 2 Examples in which a compound represented by the formula (IV) isused as a Terminal modifier Molecular Molecular Styrene Vinyl weightweight Terminal content content distribution Mw (unit: CopolymerInitiator Monomer component modifier (% by mass) (mol %) Mw/Mn tenthousand) Copolymer (22) Initiator (2) Styrene, 1,3-Butadiene, Modifier(1) Modifier (4) 30 57 1.26 28.3 Copolymer (23) Initiator (3) Styrene,1,3-Butadiene, Modifier (1) Modifier (4) 30 57 1.28 28.0 Copolymer (24)Initiator (2) Styrene, 1,3-Butadiene, Modifier (1) Modifier (4) 45 561.25 29.2 Copolymer (25) Initiator (1) Styrene, 1,3-Butadiene, Modifier(1) Modifier (4) 30 56 1.19 27.2 Copolymer (26) Initiator (1) Styrene,1,3-Butadiene, Modifier (1) Modifier (4) 30 57 1.17 26.1 Copolymer (27)Initiator (1) 1,3-Butadiene, Modifier (1) Modifier (4) 0 13.9 1.17 25.9Copolymer (28) Initiator (1) Styrene, 1,3-Butadiene, Modifier (3)Modifier (4) 30 56 1.20 25.8 Copolymer (29) Initiator (1) Styrene,1,3-Butadiene, Modifier (3) Modifier (4) 30 58 1.18 26.2 Copolymer (30)n-Butyllithium solution Styrene, 1,3-Butadiene Modifier (4) 30 56 1.1427.1 Copolymer (31) Initiator (1) 1,3-Butadiene, Modifier (3) Modifier(4) 0 14.1 1.21 26.2 Copolymer (32) Initiator (1) 1,3-Butadiene,Modifier (3) Modifier (4) 0 14.2 1.18 26.8

TABLE 3 Examples in which a compound represented by the formula (IIIb)is used as a Terminal modifier Molecular Molecular Styrene Vinyl weightweight Terminal content content distribution Mw (unit: CopolymerInitiator Monomer component modifier (% by mass) (mol %) Mw/Mn tenthousand) Copolymer (33) Initiator (2) Styrene, 1,3-Butadiene, Modifier(1) Modifier (5) 30 57 1.18 27.1 Copolymer (34) Initiator (3) Styrene,1,3-Butadiene, Modifier (1) Modifier (5) 30 56 1.16 26.3 Copolymer (35)Initiator (2) Styrene, 1,3-Butadiene, Modifier (1) Modifier (5) 45 561.16 24.6 Copolymer (36) Initiator (1) Styrene, 1,3-Butadiene, Modifier(1) Modifier (5) 30 57 1.12 24.9 Copolymer (37) Initiator (1) Styrene,1,3-Butadiene, Modifier (1) Modifier (5) 30 56 1.13 26.7 Copolymer (38)Initiator (1) Styrene, 1,3-Butadiene, Modifier (3) Modifier (5) 30 561.13 25.6 Copolymer (39) Initiator (1) Styrene, 1,3-Butadiene, Modifier(3) Modifier (5) 30 56 1.10 25.5 Copolymer (40) Initiator (1) Styrene,1,3-Butadiene, Modifier (3) Modifier (6) 30 57 1.14 252 Copolymer (41)Initiator (1) Styrene, 1,3-Butadiene, Modifier (3) Modifier (7) 30 561.15 25.9 Copolymer (42) n-Butyllithium solution Styrene, 1,3-ButadieneModifier (5) 30 55 1.09 26.3

TABLE 4 Examples in which a compound containing an alkoxysilyl group, anitrogen atom and a carbonyl group is used as a Terminal modifierMolecular Molecular Styrene Vinyl weight weight Terminal content contentdistribution Mw (unit: Copolymer Initiator Monomer component modifier (%by mass) (mol %) Mw/Mn ten thousand) Copolymer (43) Initiator (2)Styrene, 1,3-Butadiene, Modifier (1) Modifier (8) 30 56 1.24 27.5Copolymer (44) Initiator (3) Styrene, 1,3-Butadiene, Modifier (1)Modifier (8) 30 56 1.22 28.3 Copolymer (45) Initiator (2) Styrene,1,3-Butadiene, Modifier (1) Modifier (8) 45 57 1.23 27.8 Copolymer (46)Initiator (1) Styrene, 1,3-Butadiene, Modifier (1) Modifier (8) 30 561.20 28.5 Copolymer (47) Initiator (1) Styrene, 1,3-Butadiene, Modifier(1) Modifier (8) 30 55 1.19 28.6 Copolymer (48) Initiator (1) Styrene,1,3-Butadiene, Modifier (3) Modifier (8) 30 56 1.22 28.3 Copolymer (49)n-Butyllithium solution Styrene, 1,3-Butadiene Modifier (8) 30 56 1.1627.3

TABLE 5 Examples in which an N,N-dialkyl-substituted carboxylic acidamide dialkyl acetal compound is used as a Terminal modifier MolecularMolecular Styrene Vinyl weight weight Terminal content contentdistribution Mw (unit: Copolymer Initiator Monomer component modifier (%by mass) (mol %) Mw/Mn ten thousand) Copolymer (50) Initiator (2)Styrene, 1,3-Butadiene, Modifier (1) Modifier (9) 30 57 1.20 27.2Copolymer (51) Initiator (3) Styrene, 1,3-Butadiene, Modifier (1)Modifier (9) 30 56 1.21 27.3 Copolymer (52) Initiator (2) Styrene,1,3-Butadiene, Modifier (1) Modifier (9) 45 55 1.21 27.8 Copolymer (53)Initiator (1) Styrene, 1,3-Butadiene, Modifier (1) Modifier (9) 30 561.20 27.6 Copolymer (54) Initiator (1) Styrene, 1,3-Butadiene, Modifier(1) Modifier (9) 30 56 1.19 26.9 Copolymer (55) Initiator (1) Styrene,1,3-Butadiene, Modifier (3) Modifier (9) 30 57 1.18 26.8 Copolymer (56)n-Butyllithium solution Styrene, 1,3-Butadiene Modifier (9) 30 57 1.1727.1

The following describes the various chemicals used in the examples andcomparative examples.

Copolymers (1) to (56): synthesized as above

Natural Rubber: TSR20

Polybutadiene rubber: Ubepol BR150B produced by Ube Industries, Ltd.

Silica 1: ZEOSIL 1085GR produced by Rhodia (nitrogen adsorption specificsurface area: 80 m²/g)

Silica 2: ZEOSIL 115GR produced by Rhodia (nitrogen adsorption specificsurface area: 110 m²/g)

Silica 3: ZEOSIL 1165 MP produced by Rhodia (nitrogen adsorptionspecific surface area: 160 m²/g)

Silica 4: ZEOSIL 1205 MP produced by Rhodia (nitrogen adsorptionspecific surface area: 200 m²/g)

Silane coupling agent A: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide)produced by Evonik Degussa

Silane coupling agent B: Si363 produced by Evonik Degussa

Silane coupling agent C: NXT-Z45 (a compound containing linking unit Aand linking unit B (linking unit A: 55 mol %, linking unit B: 45 mol %))produced by Momentive Performance Materials

Carbon black: Diablack N339 (N₂SA: 96 m²/g, DBP absorption: 124 mL/100g) produced by Mitsubishi Chemical Corporation

Coumarone indene resin 1 (solid resin): NOVARES C90 (Tg: 90° C.)produced by Rutgers chemicals AG

Coumarone indene resin 2 (liquid resin): NOVARES C30 (Tg: 10° C.)produced by Rutgers chemicals AG

Coumarone indene resin 3 (liquid resin): NOVARES C10 (Tg: −30° C.)produced by Rutgers chemicals AG

α-Methylstyrene resin (copolymer of α-methyl styrene and styrene, solidresin): SYLVARES SA8.5 (Tg: 95° C.) produced by Arizona Chemical

Oil: X-140 produced by JX Nippon Oil & Energy Corporation

Antioxidant: Antigene 3C produced by Sumitomo Chemical Co., Ltd.

Stearic acid: TSUBAKI stearic acid beads produced by NOF Corporation

Zinc oxide: Zinc oxide #1 produced by Mitsui Mining & Smelting Co., Ltd.

Wax: Sunnoc N produced by Ouchi Shinko Chemical Industrial Co., Ltd.

Sulfur: sulfur powder produced by Tsurumi Chemical Industry Co., Ltd.

Vulcanization accelerator 1: Soxinol CZ produced by Sumitomo ChemicalCo., Ltd.

Vulcanization accelerator 2: Soxinol D produced by Sumitomo ChemicalCo., Ltd.

EXAMPLES AND COMPARATIVE EXAMPLES

According to each of the formulations shown in Tables 6 to 25, thematerials other than the sulfur and vulcanization accelerators werekneaded for 5 minutes at 150° C. using a 1.7-L Banbury mixer (producedby Kobe Steel, Ltd.) to give a kneadate. The sulfur and vulcanizationaccelerators were then added to the kneadate, followed by kneading for 5minutes at 80° C. using an open roll mill to give an unvulcanized rubbercomposition. The unvulcanized rubber composition was press-vulcanizedfor 20 minutes at 170° C. in a 0.5 mm-thick mold to obtain a vulcanizedrubber composition.

Separately, the unvulcanized rubber composition was formed into a treadshape and assembled with other tire components on a tire buildingmachine to form an unvulcanized tire. The unvulcanized tire wasvulcanized for 12 minutes at 170° C. to prepare a test tire (size:195/65R15).

<Evaluation Items and Test Methods>

In the evaluations below, Comparative Example 1 was considered as astandard comparative example in Tables 6 to 13; Comparative Example 22was considered as a standard comparative example in Tables 14 to 19; andComparative Example 40 was considered as a standard comparative examplein Tables 20 to 25.

<Mixing and Kneading Processability Index>

The Mooney viscosity (ML₁₊₄/130° C.) of each unvulcanized rubbercomposition was determined in accordance with JIS K6300-1:2001 “Rubber,unvulcanized—Physical property—Part 1: Determination of Mooney viscosityand pre-vulcanization characteristics with Mooney viscometer” using aMooney viscosity tester. That is, under a temperature condition of 130°C. achieved by 1 minute pre-heating, the Mooney viscosity of theunvulcanized rubber composition was measured after a small rotor wasrotated for 4 minutes. The result is expressed as an index. A largervalue indicates a lower Mooney viscosity, which in turn indicates bettermixing and kneading processability. The index was calculated based onthe following equation.(Mixing and kneading processability index)=(Mooney viscosity of standardcomparative example)/(Mooney viscosity of each formulation)×100<Low-Heat-Build-Up Property>

The tan δ of each vulcanized rubber composition was measured at adynamic strain amplitude of 1%, a frequency of 10 Hz, and at atemperature of 50° C. using a spectrometer (produced by UeshimaSeisakusho Co., Ltd.). The reciprocal value of the tan δ is expressed asan index relative to that of a standard comparative example (regarded as100). A larger index indicates a smaller rolling resistance (less heatbuild-up), which in turn indicates better fuel economy.

<Tan δ Peak Temperature>

The tan δ of each vulcanized rubber composition was measured at adynamic strain amplitude of 1%, a frequency of 10 Hz, a rate oftemperature rise of 2° C./min., and at a measurement temperature rangingfrom −80 to 80° C. using a spectrometer (produced by Ueshima SeisakushoCo., Ltd.). The temperature at which tan δ reached its peak wasdetermined as a tan δ peak temperature.

<Rubber Strength Index>

Each sample was subjected to a tensile test in accordance with JIS K6251:2010 to measure the elongation at break. The measurement result wasexpressed as an index relative to the result of a standard comparativeexample (regarded as 100). A larger index indicates larger rubberstrength (tensile strength).(Rubber strength index)=(Elongation at break of eachformulation)/(Elongation at break of Comparative Example 1)×100<Abrasion Resistance Index>

The volume loss of each vulcanized rubber composition was measured witha laboratory abrasion and skid tester (LAT tester) at a load of 50 N, aspeed of 20 km/h, and a slip angle of 5 degrees. The values (abrasionresistance index) in Tables 6 to 25 are relative values to the volumeloss in the standard comparative example regarded as 100. A larger valueindicates better abrasion resistance.

<Wet-Grip Performance Index>

The test tires of each example were mounted on all the wheels of avehicle (front-engine, front-wheel drive (FF) vehicle, 2000 cc, made inJapan). The braking distance from an initial speed of 100 km/h wasdetermined on a wet asphalt road surface. The result is expressed as anindex. A larger index indicates better wet-skid performance (wet-gripperformance). The index was calculated based on the following equation.(Wet-grip performance index)=(Braking distance in standard comparativeexample)/(Braking distance of each formulation)×100<Handling Stability>

The test tires of each example were mounted on all the wheels of afront-engine, front-wheel drive (FF) vehicle (2000 cc, made in Japan),and the vehicle was driven on a test course (dry road surface). Thehandling stability was evaluated based on sensory evaluation by adriver. The evaluation was scored on a scale of 1 to 10 relative to theevaluation of the standard comparative example being given 6. A higherscore indicates better handling stability.

TABLE 6 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Example 1 2 3 4 5 6 7 8 9 10 FormulationCopolymer (1) 65 — — — — — — — — — (parts by mass) Copolymer (2) — 65 —— — — — — — — Copolymer (3) — — 65 — — — — — — — Copolymer (4) — — — 65— — — — — — Copolymer (5) — — — — 65 — — — — — Copolymer (6) — — — — — —— 15 — — Copolymer (7) — — — — — 65 — — — — Copolymer (8) — — — — — — —65 65 65 Copolymer (9) — — — — — — — — — — Copolymer (10) — — — — — — —— — — Copolymer (11) — — — — — — — — — — Copolymer (12) — — — — — — — —— — Copolymer (13) — — — — — — 65 — — — Copolymer (14) — — — — — — — — —— Copolymer (15) — — — — — — — — — — Copolymer (16) — — — — — — — — — —Copolymer (17) — — — — — — — — — — Copolymer (18) — — — — — — — — 15 —Copolymer (19) — — — — — — — — — — Copolymer (20) — — — — — — — — — —Copolymer (21) — — — — — — — — — 15 Natural rubber 20 20 20 20 20 20 2020 20 20 Polybutadiene rubber 15 15 15 15 15 15 15 — — — Silica 2 (N₂SA:75 75 75 75 75 75 75 75 75 75 110 m²/g) Silane coupling agent A 6 6 6 66 6 6 6 6 6 Carbon black 5 5 5 5 5 5 5 5 5 5 Oil 20 20 20 20 20 20 20 2020 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 22 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 Vulcanization 1.8 1.8 1.81.8 1.8 1.8 1.8 1.8 1.8 1.8 accelerator 1 Vulcanization 1.2 1.2 1.2 1.21.2 1.2 1.2 1.2 1.2 1.2 accelerator 2 Evaluation Mixing and kneading 104105 102 110 100 101 105 100 100 103 processability indexLow-heat-build-up 130 132 131 144 141 143 113 130 135 115 property indextan δ peak temperature −15 −15 −15 −15 −15 −15 −15 −15 −15 −15 Rubberstrength index 102 103 104 101 100 100 103 100 100 101 Abrasionresistance 103 104 103 101 102 104 103 102 104 100 index Wet-gripperformance 113 113 112 111 111 114 109 108 109 107 index Handlingstability 6.25 6.25 6.25 6.25 6.25 6.25 6.25 6 6 6 Comparative Example 12 3 4 5 6 7 8 9 10 11 Formulation Copolymer (1) — — — — — — — — — — —(parts by mass) Copolymer (2) — — — — — — — — — — — Copolymer (3) — — —— — — — — — — — Copolymer (4) — — — — — — — — — — — Copolymer (5) — — —— — — — — — — — Copolymer (6) — — — — — — — — — — — Copolymer (7) — — —— — — — — — — — Copolymer (8) 65 — — — — — — — 65 65 65 Copolymer (9) —— — — — — — — 15 — — Copolymer (10) — 65 — — — — — — — — — Copolymer(11) — — 65 — — — — — — — — Copolymer (12) — — — 65 — — — — — — —Copolymer (13) — — — — — — — — — — — Copolymer (14) — — — — 65 — — — — —— Copolymer (15) — — — — — 65 — — — — — Copolymer (16) — — — — — — 65 —— — — Copolymer (17) — — — — — — — 65 — — — Copolymer (18) — — — — — — —— — — — Copolymer (19) — — — — — — — — — 15 — Copolymer (20) — — — — — —— — — — 15 Copolymer (21) — — — — — — — — — — — Natural rubber 20 20 2020 20 20 20 20 20 20 20 Polybutadiene rubber 15 15 15 15 15 15 15 15 — —— Silica 2 (N₂SA: 75 75 75 75 75 75 75 75 75 75 75 110 m²/g) Silanecoupling agent A 6 6 6 6 6 6 6 6 6 6 6 Carbon black 5 5 5 5 5 5 5 5 5 55 Oil 20 20 20 20 20 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1Sulfur 2 2 2 2 2 2 2 2 2 2 2 Vulcanization 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 accelerator 1 Vulcanization 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 1.2 accelerator 2 Evaluation Mixing and kneading 100 100 9796 95 93 92 92 96 98 102 processability index Low-heat-build-up 100 9598 92 99 98 97 101 104 107 98 property index tan δ peak temperature −15−15 −15 −15 −15 −15 −15 −15 −15 −15 −15 Rubber strength index 100 105103 108 103 102 104 102 99 97 99 Abrasion resistance 100 101 99 97 93 9296 88 101 102 95 index Wet-grip performance 100 101 101 96 96 97 96 100105 104 102 index Handling stability 6 6 6 6 66 6 6 6 5.5 5.5 5.5

TABLE 7 Examples in which a compound represented by the formula (IV) isused as a Terminal modifier Example Comparative Example Example 11 12 1314 15 16 17 1 4 5 6 10 12 18 19 20 Formulation Copolymer (8) — — — — — —— 65 — — — 65 — 65 65 65 (parts by Copolymer (12) — — — — — — — — 65 — —— — — — — mass) Copolymer (14) — — — — — — — — — 65 — — — — — —Copolymer (15) — — — — — — — — — — 65 — — — — — Copolymer (19) — — — — —— — — — — — 15 — — — — Copolymer (22) 65 — — — — — — — — — — — — — — —Copolymer (23) — 65 — — — — — — — — — — — — — — Copolymer (24) — — 65 —— — — — — — — — — — — — Copolymer (25) — — — 65 — — — — — — — — — — — —Copolymer (26) — — — — 65 — — — — — — — — — — — Copolymer (27) — — — — —— — — — — — — — 15 — — Copolymer (28) — — — — — 65 — — — — — — — — — —Copolymer (29) — — — — — — 65 — — — — — — — — — Copolymer (30) — — — — —— — — — — — — 65 — — — Copolymer (31) — — — — — — — — — — — — — — 15 —Copolymer (32) — — — — — — — — — — — — — — — 15 Natural rubber 20 20 2020 20 20 20 20 20 20 20 20 20 20 20 20 Polybutadiene 15 15 15 15 15 1515 15 15 15 15 — 15 — — — rubber Silica 2 (N₂SA: 75 75 75 75 75 75 75 7575 75 75 75 75 75 75 75 110 m²/g) Silane coupling 6 6 6 6 6 6 6 6 6 6 66 6 6 6 6 agent A Carbon black 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 Oil 20 2020 20 20 20 20 20 20 20 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 22 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 22 2 2 2 2 2 2 2 2 2 2 2 2 Vulcanization 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 accelerator 1 Vulcanization 1.2 1.2 1.21.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 accelerator 2Evaluation Mixing and kneading 100 101 104 100 106 107 103 100 96 95 9398 98 100 102 100 processability index Low-heat-build-up 135 130 129 128125 123 113 100 92 99 98 107 95 103 110 105 property index tan δ peak−15 −15 −15 −15 −15 −15 −15 −15 −15 −15 −15 −15 −15 −15 −15 −15temperature Rubber strength 105 104 104 105 106 103 107 100 108 103 10297 103 101 103 102 index Abrasion resistance 111 108 112 111 109 110 112100 97 93 92 102 98 108 110 112 index Wet-grip 110 109 108 106 112 109107 100 96 96 97 104 97 104 108 106 performance index Handling stability6 6 6 6 6 6 6 6 6 6 6 5.5 6 6 6 6

TABLE 8 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Com. Com. Ex. Ex. Ex. 1 4 6 21 22 23 2425 26 27 13 Formulation Copolymer (7) — — 65 65 65 65 65 65 65 65 65(parts by mass) Copolymer (8) 65 — — — — — — — — — — Copolymer (12) — 65— — — — — — — — — Natural rubber 20 20 20 20 20 20 20 20 20 20 20Polybutadiene rubber 15 15 15 15 15 15 15 15 15 15 15 Silica 1 (N₂SA: 80m²/g) — — — — — — — — — — — Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 7575 60 15 37.5 6 Silica 3 (N₂SA: 160 m²/g) — — — — — — — 15 60 37.5 3Silica 4 (N₂SA: 200 m²/g) — — — — — — — — — — — Silane coupling agent A6 6 6 — — 1.5 1.5 — — — — Silane coupling agent B — — — 6 — 6 — — — — —Silane coupling agent C — — — — 3.75 — 3.75 3.75 3.75 3.75 3.75 Carbonblack 5 5 5 5 5 5 5 5 5 5 5 Coumarone indene resin 1 — — — — — — — — — —— (Tg: 90° C.) Coumarone indene resin 2 — — — — — — — — — — — (Tg: 10°C.) Coumarone indene resin 3 — — — — — — — — — — — (Tg: −30° C.)α-Methyl styrene resin — — — — — — — — — — — (Tg: 95° C.) Oil 20 20 2020 20 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.52.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 22 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 Evaluation Mixing and kneading 100 96 101 102 106 105 110105 100 103 125 processability index Low-heat-build-up 100 92 143 145148 145 148 146 135 140 160 property index tan δ peak temperature −15−15 −15 −15 −15 −15 −15 −15 −15 −15 −15 Rubber strength index 100 108100 101 105 103 106 108 115 110 80 Abrasion resistance index 100 97 104100 102 102 105 105 110 108 75 Wet-grip performance index 100 96 114 115115 115 115 116 118 117 75 Handling stability 6 6 6.25 6.25 6.25 6.256.5 6.25 6.5 6.5 4 Com. Com. Ex. Ex. Ex. 14 28 29 30 31 32 33 34 35 3615 Formulation Copolymer (7) 65 65 65 65 65 65 65 65 65 55 100 (parts bymass) Copolymer (8) — — — — — — — — — — — Copolymer (12) — — — — — — — —— — — Natural rubber 20 20 20 20 20 20 20 20 20 30 — Polybutadienerubber 15 15 15 15 15 15 15 15 15 15 — Silica 1 (N₂SA: 80 m²/g) — 60 60— — — — — — — — Silica 2 (N₂SA: 110 m²/g) 120 — — 60 75 75 75 75 60 7575 Silica 3 (N₂SA: 160 m²/g) 40 15 — — — — — — 15 — — Silica 4 (N₂SA:200 m²/g) — — 15 15 — — — — — — — Silane coupling agent A — — — — — — —— — 6 6 Silane coupling agent B — — — — — — — — — — — Silane couplingagent C 3.75 3.75 3.75 3.75 3.75 3.75 3.75 3.75 3.75 — — Carbon black 55 5 5 5 5 5 5 5 5 5 Coumarone indene resin 1 — — — — 10 — 10 10 10 — —(Tg: 90° C.) Coumarone indene resin 2 — — — — — — 5 — — — — (Tg: 10° C.)Coumarone indene resin 3 — — — — — — — 5 — — — (Tg: −30° C.) α-Methylstyrene resin — — — — — 10 — — — — — (Tg: 95° C.) Oil 20 20 20 20 10 105 5 10 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5Stearic acid 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 22 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 Evaluation Mixing and kneading 80 115 110 100 104 105 104 103 105106 90 processability index Low-heat-build-up 75 152 150 145 138 145 137140 146 132 100 property index tan δ peak temperature −15 −15 −15 −7 −8−7 −12 −15 −15 −15 −15 Rubber strength index 90 102 104 108 106 105 106107 108 115 95 Abrasion resistance index 85 100 103 106 100 101 100 100105 106 90 Wet-grip performance index 128 115 116 117 120 125 122 124116 102 120 Handling stability 6.5 6 6.25 6.25 6.5 6.25 6.5 6.5 6.256.25 6.5

TABLE 9 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Example 37 38 39 40 41 21 42 43 44 45Formulation Copolymer (1) 65 — — — — — — — — — (parts by mass) Copolymer(2) — 65 — — — — — — — — Copolymer (3) — — 65 — — — — — — — Copolymer(4) — — — 65 — — — — — — Copolymer (5) — — — — 65 — — — — — Copolymer(6) — — — — — — — 15 — — Copolymer (7) — — — — — 65 — — — — Copolymer(8) — — — — — — — 65 65 65 Copolymer (9) — — — — — — — — — — Copolymer(10) — — — — — — — — — — Copolymer (11) — — — — — — — — — — Copolymer(12) — — — — — — — — — — Copolymer (13) — — — — — — 65 — — — Copolymer(14) — — — — — — — — — — Copolymer (15) — — — — — — — — — — Copolymer(16) — — — — — — — — — — Copolymer (17) — — — — — — — — — — Copolymer(18) — — — — — — — — 15 — Copolymer (19) — — — — — — — — — — Copolymer(20) — — — — — — — — — — Copolymer (21) — — — — — — — — — 15 Naturalrubber 20 20 20 20 20 20 20 20 20 20 Polybutadiene rubber 15 15 15 15 1515 15 — — — Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 75 75Silane coupling agent B 6 6 6 6 6 6 6 6 6 6 Silane coupling agent C — —— — — — — — — — Carbon black 5 5 5 5 5 5 5 5 5 5 Oil 20 20 20 20 20 2020 20 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearicacid 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 Wax 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 Vulcanizationaccelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixingand kneading 105 106 103 111 101 102 106 101 101 104 processabilityindex Low-heat-build-up property 132 134 133 146 143 145 115 132 137 117index tan δ peak temperature −15 −15 −15 −15 −15 −15 −15 −15 −15 −15Rubber strength index 103 104 105 102 101 101 104 101 101 102 Abrasionresistance index 99 100 99 97 98 100 99 98 100 96 Wet-grip performanceindex 110 110 109 110 108 115 115 115 115 115 Handling stability 6.256.25 6.25 6.25 6.25 6.25 6.25 6 6 6 Example 46 47 48 49 50 22 51 52 5354 Formulation Copolymer (1) 65 — — — — — — — — — (parts by mass)Copolymer (2) — 65 — — — — — — — — Copolymer (3) — — 65 — — — — — — —Copolymer (4) — — — 65 — — — — — — Copolymer (5) — — — — 65 — — — — —Copolymer (6) — — — — — — 15 — — — Copolymer (7) — — — — — 65 — — — —Copolymer (8) — — — — — — — 65 65 65 Copolymer (9) — — — — — — — — — —Copolymer (10) — — — — — — — — — — Copolymer (11) — — — — — — — — — —Copolymer (12) — — — — — — — — — — Copolymer (13) — — — — — — 65 — — —Copolymer (14) — — — — — — — — — — Copolymer (15) — — — — — — — — — —Copolymer (16) — — — — — — — — — — Copolymer (17) — — — — — — — — — —Copolymer (18) — — — — — — — — 15 — Copolymer (19) — — — — — — — — — —Copolymer (20) — — — — — — — — — — Copolymer (21) — — — — — — — — — 15Natural rubber 20 20 20 20 20 20 20 20 20 20 Polybutadiene rubber 15 1515 15 15 15 15 — — — Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 7575 75 Silane coupling agent B — — — — — — — — — — Silane coupling agentC 3.75 3.75 3.75 3.75 3.75 3.75 3.75 3.75 3.75 3.75 Carbon black 5 5 5 55 5 5 5 5 5 Oil 20 20 20 20 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 Zinc oxide2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 Sulfur 22 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 Evaluation Mixing and kneading 109 110 107 115 105 106 110105 105 108 processability index Low-heat-build-up property 135 137 136149 146 148 118 135 140 120 index tan δ peak temperature −15 −15 −15 −15−15 −15 −15 −15 −15 −15 Rubber strength index 107 108 109 106 105 105108 105 105 106 Abrasion resistance index 101 102 101 99 100 102 101 100102 98 Wet-grip performance index 114 114 113 112 112 115 110 109 110108 Handling stability 6.25 6.25 6.25 6.25 6.25 6.25 6 6 6 6

TABLE 10 Examples in which a compound represented by the formula (IV) isused as a Terminal modifier Example 55 56 57 58 59 60 61 62 63 64Formulation Copolymer (8) — — — — — — — 65 65 65 (parts by mass)Copolymer (22) 65 — — — — — — — — — Copolymer (23) — 65 — — — — — — — —Copolymer (24) — — 65 — — — — — — — Copolymer (25) — — — 65 — — — — — —Copolymer (26) — — — — 65 — — — — — Copolymer (27) — — — — — — — 15 — —Copolymer (28) — — — — — 65 — — — — Copolymer (29) — — — — — — 65 — — —Copolymer (30) — — — — — — — — — — Copolymer (31) — — — — — — — — 15 —Copolymer (32) — — — — — — — — — 15 Natural rubber 20 20 20 20 20 20 2020 20 20 Polybutadiene rubber 15 15 15 15 15 15 15 — — — Silica 2 (N₂SA:110 m²/g) 75 75 75 75 75 75 75 75 75 75 Silane coupling agent B 6 6 6 66 6 6 6 6 6 Silane coupling agent C — — — — — — — — — — Carbon black 5 55 5 5 5 5 5 5 5 Oil 20 20 20 20 20 20 20 20 20 20 Antioxidant 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 Zincoxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1Sulfur 2 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 1.2 1.2 Evaluation Mixing and kneading 98 99 102 98 104 105101 98 100 98 processability index Low-heat-build-up property 143 138137 136 133 131 121 111 118 113 index tan δ peak temperature −20 −20 −20−20 −20 −20 −20 −20 −20 −20 Rubber strength index 105 104 104 105 106103 107 101 103 102 Abrasion resistance index 107 104 108 107 105 106108 104 106 108 Wet-grip performance index 113 112 111 109 115 112 110107 111 109 Handling stability 6 6 6 6 6 6 6 6 6 6 Example 65 66 67 6869 70 71 72 73 74 Formulation Copolymer (8) — — — — — — — 65 65 65(parts by mass) Copolymer (22) 65 — — — — — — — — — Copolymer (23) — 65— — — — — — — — Copolymer (24) — — 65 — — — — — — — Copolymer (25) — — —65 — — — — — — Copolymer (26) — — — — 65 — — — — — Copolymer (27) — — —— — — — 15 — — Copolymer (28) — — — — — 65 — — — — Copolymer (29) — — —— — — 65 — — — Copolymer (30) — — — — — — — — — — Copolymer (31) — — — —— — — — 15 — Copolymer (32) — — — — — — — — — 15 Natural rubber 20 20 2020 20 20 20 20 20 20 Polybutadiene rubber 15 15 15 15 15 15 15 — — —Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 75 75 Silane couplingagent B — — — — — — — — — — Silane coupling agent C 3.75 3.75 3.75 3.753.75 3.75 3.75 3.75 3.75 3.75 Carbon black 5 5 5 5 5 5 5 5 5 5 Oil 20 2020 20 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2Evaluation Mixing and kneading 104 105 108 104 110 111 107 104 106 104processability index Low-heat-build-up property 143 138 137 136 133 131121 111 118 113 index tan δ peak temperature −20 −20 −20 −20 −20 −20 −20−20 −20 −20 Rubber strength index 109 108 108 109 110 107 111 105 107106 Abrasion resistance index 109 106 110 109 107 108 110 106 108 110Wet-grip performance index 113 112 111 109 115 112 110 107 111 109Handling stability 6 6 6 6 6 6 6 6 6 6

TABLE 11 Examples in which a compound represented by the formula (IIIb)is used as a Terminal modifier Example 75 76 77 78 79 80 81 82 83 84 85Formulation Copolymer (33) 65 — — — — — — — — 65 — (parts by Copolymer(34) — 65 — — — — — — — — 65 mass) Copolymer (35) — — 65 — — — — — — — —Copolymer (36) — — — 65 — — — — — — — Copolymer (37) — — — — 65 — — — —— — Copolymer (38) — — — — — 65 — — — — — Copolymer (39) — — — — — — 65— — — — Copolymer (40) — — — — — — — 65 — — — Copolymer (41) — — — — — —— — 65 — — Copolymer (42) — — — — — — — — — — — Natural rubber 20 20 2020 20 20 20 20 20 20 20 Polybutadiene rubber 15 15 15 15 15 15 15 15 1515 15 Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 75 75 75 Silanecoupling agent B 6 6 6 6 6 6 6 6 6 — — Silane coupling agent C — — — — —— — — — 3.75 3.75 Carbon black 5 5 5 5 5 5 5 5 5 5 5 Oil 20 20 20 20 2020 20 20 20 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 22 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 Evaluation Mixing and kneading process- 102 107 103 102 103 107102 103 101 107 112 ability index Low-heat-build-property index 123 119120 113 123 110 120 106 104 127 123 tan δ peak temperature −15 −15 −15−15 −15 −15 −15 −15 −15 −15 −15 Rubber strength index 103 104 103 105102 105 103 107 105 108 109 Abrasion resistance index 102 102 101 104102 103 101 104 103 100 100 Wet-grip performance index 104 104 103 113103 112 106 109 108 105 105 Handling stability 6 6 6 6 6 6 6 6 6 6 6Example Com. Ex. 86 87 88 89 90 91 92 16 17 Formulation Copolymer (33) —— — — — — — — — (parts by Copolymer (34) — — — — — — — — — mass)Copolymer (35) 65 — — — — — — — — Copolymer (36) — 65 — — — — — — —Copolymer (37) — — 65 — — — — — — Copolymer (38) — — — 65 — — — — —Copolymer (39) — — — — 65 — — — — Copolymer (40) — — — — — 65 — — —Copolymer (41) — — — — — — 65 — — Copolymer (42) — — — — — — — 65 65Natural rubber 20 20 20 20 20 20 20 20 20 Polybutadiene rubber 15 15 1515 15 15 15 15 15 Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 75Silane coupling agent B — — — — — — — 6 — Silane coupling agent C 3.753.75 3.75 3.75 3.75 3.75 3.75 — 3.75 Carbon black 5 5 5 5 5 5 5 5 5 Oil20 20 20 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Stearic acid 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 Vulcanizationaccelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing andkneading process- 108 107 108 112 107 108 106 90 94 ability indexLow-heat-build-property index 124 117 127 114 124 110 108 95 98 tan δpeak temperature −15 −15 −15 −15 −15 −15 −15 −15 −15 Rubber strengthindex 108 110 107 110 108 112 110 97 102 Abrasion resistance index 99102 100 101 99 102 101 95 93 Wet-grip performance index 104 114 104 113107 110 109 102 103 Handling stability 6 6 6 6 6 6 6 6 6

TABLE 12 Examples in which a compound containing an alkoxysilyl group, anitrogen atom and a carbonyl group is used as a Terminal modifierExample 93 94 95 96 97 98 99 100 Formulation Copolymer (43) 65 — — — — —65 — (parts by Copolymer (44) — 65 — — — — — 65 mass) Copolymer (45) — —65 — — — — — Copolymer (46) — — — 65 — — — — Copolymer (47) — — — — 65 —— — Copolymer (48) — — — — — 65 — — Copolymer (49) — — — — — — — —Natural rubber 20 20 20 20 20 20 20 20 Polybutadiene rubber 15 15 15 1515 15 15 15 Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 Silanecoupling agent B 6 6 6 6 6 6 — — Silane coupling agent C — — — — — —3.75 3.75 Carbon black 5 5 5 5 5 5 5 5 Oil 20 20 20 20 20 20 20 20Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 Sulfur 22 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2Evaluation Mixing and kneading processability index 106 105 103 102 100105 111 110 Low-heat-build-property index 118 110 117 114 118 109 122114 tan δ peak temperature −15 −15 −15 −15 −15 −15 −15 −15 Rubberstrength index 100 102 100 101 100 103 105 107 Abrasion resistance index107 106 102 103 104 103 105 104 Wet-grip performance index 103 109 107110 111 111 104 110 Handling stability 6 6 6 6 6 6 6 6 Example Com. Ex.101 102 103 104 18 19 Formulation Copolymer (43) — — — — — — (parts byCopolymer (44) — — — — — — mass) Copolymer (45) 65 — — — — — Copolymer(46) — 65 — — — — Copolymer (47) — — 65 — — — Copolymer (48) — — — 65 —— Copolymer (49) — — — — 65 65 Natural rubber 20 20 20 20 20 20Polybutadiene rubber 15 15 15 15 15 15 Silica 2 (N₂SA: 110 m²/g) 75 7575 75 75 75 Silane coupling agent B — — — — 6 — Silane coupling agent C3.75 3.75 3.75 3.75 — 3.75 Carbon black 5 5 5 5 5 5 Oil 20 20 20 20 2020 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 Zincoxide 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing and kneadingprocessability index 108 107 105 110 92 97 Low-heat-build-property index121 118 122 113 92 95 tan δ peak temperature −15 −15 −15 −15 −15 −15Rubber strength index 105 106 105 108 96 101 Abrasion resistance index100 101 102 101 94 92 Wet-grip performance index 108 111 112 112 100 101Handling stability 6 6 6 6 6 6

TABLE 13 Examples in which an N,N-dialkyl-substituted carboxylic acidamide dialkyl acetal compound is used as a Terminal modifier Example 105106 107 108 109 110 111 112 Formulation Copolymer (50) 65 — — — — — 65 —(parts by Copolymer (51) — 65 — — — — — 65 mass) Copolymer (52) — — 65 —— — — — Copolymer (53) — — — 65 — — — — Copolymer (54) — — — — 65 — — —Copolymer (55) — — — — — 65 — — Copolymer (56) — — — — — — — — Naturalrubber 20 20 20 20 20 20 20 20 Polybutadiene rubber 15 15 15 15 15 15 1515 Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 Silane couplingagent B 6 6 6 6 6 6 — — Silane coupling agent C — — — — — — 3.75 3.75Carbon black 5 5 5 5 5 5 5 5 Oil 20 20 20 20 20 20 20 20 Antioxidant 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 Zinc oxide 2.52.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 EvaluationMixing and kneading processability index 103 105 104 104 100 106 108 110Low-heat-build-property index 119 112 110 116 115 107 123 116 tan δ peaktemperature −15 −15 −15 −15 −15 −15 −15 −15 Rubber strength index 101102 100 100 101 103 106 107 Abrasion resistance index 108 107 103 102103 102 106 105 Wet-grip performance index 102 107 111 108 113 110 103108 Handling stability 6 6 6 6 6 6 6 6 Example Com. Ex. 113 114 115 11620 21 Formulation Copolymer (50) — — — — — — (parts by Copolymer (51) —— — — — — mass) Copolymer (52) 65 — — — — — Copolymer (53) — 65 — — — —Copolymer (54) — — 65 — — — Copolymer (55) — — — 65 — — Copolymer (56) —— — — 65 65 Natural rubber 20 20 20 20 20 20 Polybutadiene rubber 15 1515 15 15 15 Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 Silane couplingagent B — — — — 6 — Silane coupling agent C 3.75 3.75 3.75 3.75 — 3.75Carbon black 5 5 5 5 5 5 Oil 20 20 20 20 20 20 Antioxidant 1.5 1.5 1.51.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5Wax 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.81.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2Evaluation Mixing and kneading processability index 109 109 105 111 9094 Low-heat-build-property index 114 120 119 111 92 95 tan δ peaktemperature −15 −15 −15 −15 −15 −15 Rubber strength index 105 105 106108 96 101 Abrasion resistance index 101 100 101 100 93 91 Wet-gripperformance index 112 109 114 111 100 101 Handling stability 6 6 6 6 6 6

TABLE 14 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Comparative Example Example 117 118 119120 121 122 123 124 125 126 22 23 Formulation Copolymer (1) 60 — — — — —— — — — — — (parts by Copolymer (2) — 60 — — — — — — — — — — mass)Copolymer (3) — — 60 — — — — — — — — — Copolymer (4) — — — 60 — — — — —— — — Copolymer (5) — — — — 60 — — — — — — — Copolymer (6) — — — — — — —20 — — — — Copolymer (7) — — — — — 60 — — — — — — Copolymer (8) — — — —— — — 60 60 60 60 — Copolymer (9) — — — — — — — — — — — — Copolymer (10)— — — — — — — — — — — 60 Copolymer (11) — — — — — — — — — — — —Copolymer (12) — — — — — — — — — — — — Copolymer (13) — — — — — — 60 — —— — — Copolymer (14) — — — — — — — — — — — — Copolymer (15) — — — — — —— — — — — — Copolymer (16) — — — — — — — — — — — — Copolymer (17) — — —— — — — — — — — — Copolymer (18) — — — — — — — — 20 — — — Copolymer (19)— — — — — — — — — — — — Copolymer (20) — — — — — — — — — — — — Copolymer(21) — — — — — — — — — 20 — — Natural rubber 20 20 20 20 20 20 20 20 2020 20 20 Polybutadiene rubber 20 20 20 20 20 20 20 — — — 20 20 Carbonblack 15 15 15 15 15 15 15 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 2525 25 25 Silica 1 (N₂SA: 80 m²/g) — — — — — — — — — — — — Silica 2(N₂SA: 110 m²/g) 60 60 60 60 60 60 60 60 60 60 60 60 Silica 3 (N₂SA: 160m²/g) 15 15 15 15 15 15 15 15 15 15 15 15 Silica 4 (N₂SA: 200 m²/g) — —— — — — — — — — — — Silane coupling agent A 6 6 6 6 6 6 6 6 6 6 6 6Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid2 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 2 2Carbon black 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Oil 1.2 1.21.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing and kneadingprocess- 105 106 103 111 101 102 106 101 101 104 100 102 ability indexLow-heat-build-property 125 127 126 138 135 137 109 125 130 111 100 96index tan δ peak temperature −14 −14 −14 −14 −14 −14 −13 −14 −13 −13 −14−14 Rubber strength index 107 108 109 106 105 105 108 105 104 106 100106 Abrasion resistance index 101 102 101 99 100 102 101 100 102 98 10099 Wet-grip performance index 114 114 113 112 112 115 110 109 110 108100 103 Handling stability 6.25 6.25 6.25 6.25 6.25 6.25 6.25 6 6 6 6 6Comparative Example 24 25 26 27 28 29 30 31 32 Formulation Copolymer (1)— — — — — — — — — (parts by Copolymer (2) — — — — — — — — — mass)Copolymer (3) — — — — — — — — — Copolymer (4) — — — — — — — — —Copolymer (5) — — — — — — — — — Copolymer (6) — — — — — — — — —Copolymer (7) — — — — — — — — — Copolymer (8) — — — — — — 60 60 60Copolymer (9) — — — — — — 20 — — Copolymer (10) — — — — — — — — —Copolymer (11) 60 — — — — — — — — Copolymer (12) — 60 — — — — — — —Copolymer (13) — — — — — — — — — Copolymer (14) — — 60 — — — — — —Copolymer (15) — — — 60 — — — — — Copolymer (16) — — — — 60 — — — —Copolymer (17) — — — — — 60 — — — Copolymer (18) — — — — — — — — —Copolymer (19) — — — — — — — 20 — Copolymer (20) — — — — — — — — 20Copolymer (21) — — — — — — — — — Natural rubber 20 20 20 20 20 20 20 2020 Polybutadiene rubber 20 20 20 20 20 20 — — — Carbon black 15 15 15 1515 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25 Silica 1 (N₂SA; 80 m²/g) —— — — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 60 60 60 60 60 60 60 60Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 15 15 15 15 15 Silica 4 (N₂SA: 200m²/g) — — — — — — — — — Silane coupling agent A 6 6 6 6 6 6 6 6 6Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 22 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 11 Sulfur 2 2 2 2 2 2 2 2 2 Carbon black 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 Oil 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing andkneading process- 98 97 96 94 93 93 97 98 102 ability indexLow-heat-build-property 99 93 100 99 98 102 105 107 98 index tan δ peaktemperature −14 −16 −14 −14 −14 −14 −14 −13 −13 Rubber strength index104 109 104 103 105 103 100 100 102 Abrasion resistance index 97 95 9190 94 87 99 100 93 Wet-grip performance index 103 98 98 99 98 102 107106 104 Handling stability 6 5.75 6 6 6 6 5.5 5.5 5.5

TABLE 15 Examples in which a compound represented by the formula (IV) isused as a Terminal modifier Comparative Example Example 127 128 129 130131 132 133 22 25 Formulation Copolymer (8) — — — — — — — 60 — (parts byCopolymer (12) — — — — — — — — 60 mass) Copolymer (14) — — — — — — — — —Copolymer (15) — — — — — — — — — Copolymer (19) — — — — — — — — —Copolymer (22) 60 — — — — — — — — Copolymer (23) — 60 — — — — — — —Copolymer (24) — — 60 — — — — — — Copolymer (25) — — — 60 — — — — —Copolymer (26) — — — — 60 — — — — Copolymer (27) — — — — — — — — —Copolymer (28) — — — — — 60 — — — Copolymer (29) — — — — — — 60 — —Copolymer (30) — — — — — — — — — Copolymer (31) — — — — — — — — —Copolymer (32) — — — — — — — — — Natural rubber 20 20 20 20 20 20 20 2020 Polybutadiene rubber 20 20 20 20 20 20 20 20 20 Carbon black 15 15 1515 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25 Silica 1 (N₂SA: 80m²/g) — — — — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 60 60 60 60 60 6060 60 Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 15 15 15 15 15 Silica 4(N₂SA: 200 m²/g) — — — — — — — — — Silane coupling agent A 6 6 6 6 6 6 66 6 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 22 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 11 1 1 Sulfur 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.81.8 1.8 1.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 1.2 Evaluation Mixing and kneading processability index 100101 104 100 106 107 103 100 97 Low-heat-build-property index 129 126 127126 122 123 113 100 93 tan δ peak temperature −14 −14 −14 −14 −14 −14−14 −14 −16 Rubber strength index 111 110 109 111 112 109 113 100 109Abrasion resistance index 109 106 110 109 107 108 110 100 95 Wet-gripperformance index 110 109 108 111 112 110 109 100 98 Handling stability6 6 6 6 6 6 6 6 5.75 Comparative Example Example 26 27 31 33 134 135 136Formulation Copolymer (8) — — 60 — 60 60 60 (parts by Copolymer (12) — —— — — — — mass) Copolymer (14) 60 — — — — — — Copolymer (15) — 60 — — —— — Copolymer (19) — — 20 — — — — Copolymer (22) — — — — — — — Copolymer(23) — — — — — — — Copolymer (24) — — — — — — — Copolymer (25) — — — — —— — Copolymer (26) — — — — — — — Copolymer (27) — — — — 20 — — Copolymer(28) — — — — — — — Copolymer (29) — — — — — — — Copolymer (30) — — — 60— — — Copolymer (31) — — — — — 20 — Copolymer (32) — — — — — — 20Natural rubber 20 20 20 20 20 20 20 Polybutadiene rubber 20 20 — 20 — —— Carbon black 15 15 15 15 15 15 15 Oil 25 25 25 25 25 25 25 Silica 1(N₂SA: 80 m²/g) — — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 60 60 60 6060 60 Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 15 15 15 Silica 4 (N₂SA: 200m²/g) — — — — — — — Silane coupling agent A 6 6 6 6 6 6 6 Antioxidant1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 Zinc oxide 2.52.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing and kneadingprocessability index 96 94 98 98 101 102 100 Low-heat-build-propertyindex 100 99 107 96 108 110 105 tan δ peak temperature −14 −14 −13 −13−13 −14 −14 Rubber strength index 104 103 100 105 109 109 108 Abrasionresistance index 91 90 100 100 106 108 110 Wet-grip performance index 9899 106 104 111 110 108 Handling stability 6 6 5.5 5.5 6 6 6

TABLE 16 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Com. Ex. Ex. Com. Ex. Ex. 22 25 122 34 35137 138 139 140 Formulation Copolymer (7) — — 60 60 60 60 60 60 60(parts by Copolymer (8) 60 — — — — — — — — mass) Copolymer (12) — 60 — —— — — — — Natural rubber 20 20 20 20 20 20 20 20 20 Polybutadiene rubber20 20 20 20 20 20 20 20 20 Carbon black 15 15 15 15 15 15 15 15 15 Oil25 25 25 25 25 25 25 25 25 Silica 1 (N₂SA: 80 m²/g) — — — — — — — 60 60Silica 2 (N₂SA: 110 m²/g) 60 60 60 6 120 35 15 — — Silica 3 (N₂SA: 160m²/g) 15 15 15 3 40 35 60 15 — Silica 4 (N₂SA: 200 m²/g) — — — — — — — —15 Silane coupling agent A 6 6 6 6 6 6 6 6 6 Coumarone indene resin 1(Tg: 90° C.) — — — — — — — — — Coumarone indene resin 2 (Tg: 10° C.) — —— — — — — — — Coumarone indene resin 3 (Tg: −30° C.) — — — — — — — — —α-Methyl styrene resin (Tg: 95° C.) — — — — — — — — — Antioxidant 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 Zincoxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 Sulfur 22 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2Evaluation Mixing and kneading processability index 100 97 102 121 86101 100 105 102 Low-heat-build-property index 100 93 137 99 121 133 130137 137 tan δ peak temperature −14 −16 −14 −14 −14 −16 −14 −14 −15Rubber strength index 100 109 105 91 125 106 111 102 107 Abrasionresistance index 100 95 102 97 83 104 107 100 103 Wet-grip performanceindex 100 98 115 96 111 115 113 113 116 Handling stability 6 5.75 6.256.25 6 6 6.25 6 6 Ex. Com. Ex. 141 142 143 144 145 146 36 FormulationCopolymer (7) 60 70 60 60 60 60 100 (parts by Copolymer (8) — — — — — —— mass) Copolymer (12) — — — — — — — Natural rubber 20 10 20 20 20 20 —Polybutadiene rubber 20 20 20 20 20 20 — Carbon black 15 15 15 15 15 1515 Oil 25 25 25 25 25 25 25 Silica 1 (N₂SA: 80 m²/g) — — — — — — —Silica 2 (N₂SA: 110 m²/g) 60 60 60 60 60 60 60 Silica 3 (N₂SA: 160 m²/g)— 15 15 15 15 15 15 Silica 4 (N₂SA: 200 m²/g) 15 — — — — — — Silanecoupling agent A 6 6 6 6 6 6 6 Coumarone indene resin 1 (Tg: 90° C.) — —10 — 10 10 — Coumarone indene resin 2 (Tg: 10° C.) — — — — 5 — —Coumarone indene resin 3 (Tg: −30° C.) — — — — — 5 — α-Methyl styreneresin (Tg: 95° C.) — — — 10 — — — Antioxidant 1.5 1.5 1.5 1.5 1.5 1.51.5 Stearic acid 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5Wax 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.81.8 1.8 1.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.21.2 1.2 Evaluation Mixing and kneading processability index 101 104 102102 108 110 82 Low-heat-build-property index 132 131 137 136 134 137 125tan δ peak temperature −16 −13 −14 −14 −14 −13 −10 Rubber strength index110 105 107 107 111 112 78 Abrasion resistance index 105 103 104 100 102105 79 Wet-grip performance index 117 109 119 121 119 121 124 Handlingstability 6 6.5 6.25 6.25 6.25 6.5 4.5

TABLE 17 Examples in which a compound represented by the formula (IIIb)is used as a Terminal modifier Example 147 148 149 150 151 152 153 154155 Formulation Copolymer (8) — — — — — — — — — (parts by Copolymer (12)— — — — — — — — — mass) Copolymer (14) — — — — — — — — — Copolymer (15)— — — — — — — — — Copolymer (19) — — — — — — — — — Copolymer (33) 60 — —— — — — — — Copolymer (34) — 60 — — — — — — — Copolymer (35) — — 60 — —— — — — Copolymer (36) — — — 60 — — — — — Copolymer (37) — — — — 60 — —— — Copolymer (38) — — — — — 60 — — — Copolymer (39) — — — — — — 60 — —Copolymer (40) — — — — — — — 60 — Copolymer (41) — — — — — — — — 60Copolymer (42) — — — — — — — — — Natural rubber 20 20 20 20 20 20 20 2020 Polybutadiene rubber 20 20 20 20 20 20 20 20 20 Carbon black 15 15 1515 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25 Silica 1 (N₂SA: 80m²/g) — — — — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 60 60 60 60 60 6060 60 Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 15 15 15 15 15 Silica 4(N₂SA: 200 m²/g) — — — — — — — — — Silane coupling agent A 6 6 6 6 6 6 66 6 Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 22 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 11 1 1 Sulfur 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.81.8 1.8 1.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 1.2 Evaluation Mixing and kneading processability index 111117 112 111 112 117 111 112 110 Low-heat-build-property index 126 121123 115 126 112 123 108 106 tan δ peak temperature −15 −15 −15 −15 −15−15 −15 −15 −15 Rubber strength index 104 105 104 106 103 106 104 108106 Abrasion resistance index 101 101 100 103 101 102 100 103 102Wet-grip performance index 104 104 103 113 103 112 106 109 108 Handlingstability 6.25 6 6 6 6.25 6.25 6 6 6 Comparative Example 22 25 26 27 3137 Formulation Copolymer (8) 60 — — — 60 — (parts by Copolymer (12) — 60— — — — mass) Copolymer (14) — — 60 — — — Copolymer (15) — — — 60 — —Copolymer (19) — — — — 20 — Copolymer (33) — — — — — — Copolymer (34) —— — — — — Copolymer (35) — — — — — — Copolymer (36) — — — — — —Copolymer (37) — — — — — — Copolymer (38) — — — — — — Copolymer (39) — —— — — — Copolymer (40) — — — — — — Copolymer (41) — — — — — — Copolymer(42) — — — — — 60 Natural rubber 20 20 20 20 20 20 Polybutadiene rubber20 20 20 20 — 20 Carbon black 15 15 15 15 15 15 Oil 25 25 25 25 25 25Silica 1 (N₂SA: 80 m²/g) — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 60 6060 60 60 Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 15 15 Silica 4 (N₂SA: 200m²/g) — — — — — — Silane coupling agent A 6 6 6 6 6 6 Antioxidant 1.51.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.52.5 2.5 Wax 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 Vulcanization accelerator 11.8 1.8 1.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.21.2 Evaluation Mixing and kneading processability index 100 97 96 94 9898 Low-heat-build-property index 100 93 100 99 107 97 tan δ peaktemperature −14 −16 −14 −14 −13 −15 Rubber strength index 100 109 104103 100 98 Abrasion resistance index 100 95 91 90 100 94 Wet-gripperformance index 100 98 98 99 106 102 Handling stability 6 5.75 6 6 5.56

TABLE 18 Examples in which a compound containing an alkoxysilyl group, anitrogen atom and a carbonyl group is used as a Terminal modifierExample Comparative Example 156 157 158 159 160 161 22 25 26 27 31 38Formulation Copolymer (8) — — — — — — 60 — — — 60 — (parts by Copolymer(12) — — — — — — — 60 — — — — mass) Copolymer (14) — — — — — — — — 60 —— — Copolymer (15) — — — — — — — — — 60 — — Copolymer (19) — — — — — — —— — — 20 — Copolymer (43) 60 — — — — — — — — — — — Copolymer (44) — 60 —— — — — — — — — — Copolymer (45) — — 60 — — — — — — — — — Copolymer (46)— — — 60 — — — — — — — — Copolymer (47) — — — — 60 — — — — — — —Copolymer (48) — — — — — 60 — — — — — — Copolymer (49) — — — — — — — — —— — 60 Natural rubber 20 20 20 20 20 20 20 20 20 20 20 20 Polybutadienerubber 20 20 20 20 20 20 20 20 20 20 — 20 Carbon black 15 15 15 15 15 1515 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25 25 25 25 Silica 1(N₂SA: 80 m²/g) — — — — — — — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 6060 60 60 60 60 60 60 60 60 60 Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 1515 15 15 15 15 15 15 Silica 4 (N₂SA: 200 m²/g) — — — — — — — — — — — —Silane coupling agent A 6 6 6 6 6 6 6 6 6 6 6 6 Antioxidant 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 2Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 11 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 11.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 EvaluationMixing and kneading 115 114 112 111 109 114 100 97 96 94 98 100processability index Low-heat-build-property 120 112 119 116 120 111 10093 100 99 107 94 index tan δ peak temperature −15 −15 −15 −15 −15 −15−14 −16 −14 −14 −13 −15 Rubber strength index 101 103 101 102 101 104100 109 104 103 100 97 Abrasion resistance index 106 105 101 102 103 102100 95 91 90 100 93 Wet-grip performance index 103 109 107 110 111 111100 98 98 99 106 100 Handling stability 6 6 6 6 6 6 6 5.75 6 6 5.5 6

TABLE 19 Examples in which an N,N-dialkyl-substituted carboxylic acidamide dialkyl acetal compound is used as a Terminal modifier ExampleComparative Example 162 163 164 165 166 167 22 25 26 27 31 39Formulation Copolymer (8) — — — — — — 60 — — — 60 — (parts by Copolymer(12) — — — — — — — 60 — — — — mass) Copolymer (14) — — — — — — — — 60 —— — Copolymer (15) — — — — — — — — — 60 — — Copolymer (19) — — — — — — —— — — 20 — Copolymer (50) 60 — — — — — — — — — — — Copolymer (51) — 60 —— — — — — — — — — Copolymer (52) — — 60 — — — — — — — — — Copolymer (53)— — — 60 — — — — — — — — Copolymer (54) — — — — 60 — — — — — — —Copolymer (55) — — — — — 60 — — — — — — Copolymer (56) — — — — — — — — —— — 60 Natural rubber 20 20 20 20 20 20 20 20 20 20 20 20 Polybutadienerubber 20 20 20 20 20 20 20 20 20 20 — 20 Carbon black 15 15 15 15 15 1515 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25 25 25 25 Silica 1(N₂SA: 80 m²/g) — — — — — — — — — — — — Silica 2 (N₂SA: 110 m²/g) 60 6060 60 60 60 60 60 60 60 60 60 Silica 3 (N₂SA: 160 m²/g) 15 15 15 15 1515 15 15 15 15 15 15 Silica 4 (N₂SA: 200 m²/g) — — — — — — — — — — — —Silane coupling agent A 6 6 6 6 6 6 6 6 6 6 6 6 Antioxidant 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 2Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 11 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 11.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 EvaluationMixing and kneading 112 114 113 113 109 115 100 97 96 94 98 98processability index Low-heat-build-property 121 114 112 118 117 109 10093 100 99 107 94 index tan δ peak temperature −15 −15 −15 −15 −15 −15−14 −16 −14 −14 −13 −15 Rubber strength index 102 103 101 101 102 104100 109 104 103 100 97 Abrasion resistance index 107 106 102 101 102 101100 95 91 90 100 92 Wet-grip performance index 102 107 111 108 113 110100 98 98 99 106 100 Handling stability 6 6 6 6 6 6 6 5.75 6 6 5.5 6

TABLE 20 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Comparative Example Example 168 169 170171 172 173 174 175 176 177 40 41 Formulation Copolymer (1) 60 — — — — —— — — — — — (parts by Copolymer (2) — 60 — — — — — — — — — — mass)Copolymer (3) — — 60 — — — — — — — — — Copolymer (4) — — — 60 — — — — —— — — Copolymer (5) — — — — 60 — — — — — — — Copolymer (6) — — — — — — —20 — — — — Copolymer (7) — — — — — 60 — — — — — — Copolymer (8) — — — —— — — 60 60 60 60 — Copolymer (9) — — — — — — — — — — — — Copolymer (10)— — — — — — — — — — — 60 Copolymer (11) — — — — — — — — — — — —Copolymer (12) — — — — — — — — — — — — Copolymer (13) — — — — — — 60 — —— — — Copolymer (14) — — — — — — — — — — — — Copolymer (15) — — — — — —— — — — — — Copolymer (16) — — — — — — — — — — — — Copolymer (17) — — —— — — — — — — — — Copolymer (18) — — — — — — — — 20 — — — Copolymer (19)— — — — — — — — — — — — Copolymer (20) — — — — — — — — — — — — Copolymer(21) — — — — — — — — — 20 — — Natural rubber 20 20 20 20 20 20 20 20 2020 20 20 Polybutadiene rubber 20 20 20 20 20 20 20 — — — 20 20 Silica 2(N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 75 75 75 75 Silane couplingagent A 6 6 6 6 6 6 6 6 6 6 6 6 Carbon black 15 15 15 15 15 15 15 15 1515 15 15 Oil 25 25 25 25 25 25 25 25 25 25 25 25 Coumarone indene resin1 10 10 10 10 10 10 10 10 10 10 10 10 (Tg: 90° C.) Coumarone indeneresin 2 — — — — — — — — — — — — (Tg: 10° C.) Coumarone indene resin 3 —— — — — — — — — — — — (Tg: −30° C.) α-Methyl styrene resin — — — — — — —— — — — — (Tg: 95° C.) Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.52.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 1 Sulfur 22 2 2 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.21.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing and kneading process-106 107 104 112 102 103 107 102 102 105 100 103 ability indexLow-heat-build-up property 127 129 128 140 137 139 110 127 132 113 10098 index tan δ peak temperature −14 −14 −14 −14 −14 −14 −13 −14 −13 −13−14 −14 Rubber strength index 104 105 106 103 102 102 105 102 101 103100 104 Abrasion resistance index 102 103 102 100 101 103 102 101 103 99100 100 Wet-grip performance index 112 112 111 110 110 113 108 108 109107 100 102 Handling stability 6.25 6.25 6.25 6.25 6.25 6.25 6.25 6 6 66 6 Comparative Example 42 43 44 45 46 47 48 49 50 51 FormulationCopolymer (1) — — — — — — — — — — (parts by Copolymer (2) — — — — — — —— — — mass) Copolymer (3) — — — — — — — — — — Copolymer (4) — — — — — —— — — — Copolymer (5) — — — — — — — — — — Copolymer (6) — — — — — — — —— — Copolymer (7) — — — — — — — — — — Copolymer (8) — — — — — — 60 60 6060 Copolymer (9) — — — — — — 20 — — — Copolymer (10) — — — — — — — — — —Copolymer (11) 60 — — — — — — — — — Copolymer (12) — 60 — — — — — — — —Copolymer (13) — — — — — — — — — — Copolymer (14) — — 60 — — — — — — —Copolymer (15) — — — 60 — — — — — — Copolymer (16) — — — — 60 — — — — —Copolymer (17) — — — — — 60 — — — — Copolymer (18) — — — — — — — — — —Copolymer (19) — — — — — — — 20 — — Copolymer (20) — — — — — — — — 20 —Copolymer (21) — — — — — — — — — — Natural rubber 20 20 20 20 20 20 2020 20 20 Polybutadiene rubber 20 20 20 20 20 20 — — — 20 Silica 2 (N₂SA:110 m²/g) 75 75 75 75 75 75 75 75 75 75 Silane coupling agent A 6 6 6 66 6 6 6 6 6 Carbon black 15 15 15 15 15 15 15 15 15 15 Oil 25 25 25 2525 25 25 25 25 25 Coumarone indene resin 1 10 10 10 10 10 10 10 10 10 —(Tg: 90° C.) Coumarone indene resin 2 — — — — — — — — — — (Tg: 10° C.)Coumarone indene resin 3 — — — — — — — — — — (Tg: −30° C.) α-Methylstyrene resin — — — — — — — — — — (Tg: 95° C.) Antioxidant 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 Zinc oxide2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 Sulfur 22 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 Evaluation Mixing and kneading process- 99 98 97 95 94 94 9899 103 97 ability index Low-heat-build-up property 100 95 101 100 100103 107 109 99 105 index tan δ peak temperature −14 −16 −14 −14 −14 −14−14 −13 −13 −17 Rubber strength index 102 107 102 101 103 101 98 98 10094 Abrasion resistance index 98 96 92 91 95 87 100 101 94 97 Wet-gripperformance index 102 97 98 99 98 101 107 106 104 98 Handling stability6 5.75 6 6 6 6 5.5 5.5 5.5 6.25

TABLE 21 Examples in which a compound represented by the formula (IV) isused as a Terminal modifier Comparative Example Example 178 179 180 181182 183 184 40 43 Formulation Copolymer (8) — — — — — — — 60 — (parts byCopolymer (12) — — — — — — — — 60 mass) Copolymer (14) — — — — — — — — —Copolymer (15) — — — — — — — — — Copolymer (19) — — — — — — — — —Copolymer (22) 60 — — — — — — — — Copolymer (23) — 60 — — — — — — —Copolymer (24) — — 60 — — — — — — Copolymer (25) — — — 60 — — — — —Copolymer (26) — — — — 60 — — — — Copolymer (27) — — — — — — — — —Copolymer (28) — — — — — 60 — — — Copolymer (29) — — — — — — 60 — —Copolymer (30) — — — — — — — — — Copolymer (31) — — — — — — — — —Copolymer (32) — — — — — — — — — Natural rubber 20 20 20 20 20 20 20 2020 Polybutadiene rubber 20 20 20 20 20 20 20 20 20 Silica 2 (N₂SA: 110m²/g) 75 75 75 75 75 75 75 75 75 Silane coupling agent A 6 6 6 6 6 6 6 66 Carbon black 15 15 15 15 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25Coumarone indene resin 1 (Tg: 90° C.) 10 10 10 10 10 10 10 10 10Coumarone indene resin 2 (Tg: 10° C.) — — — — — — — — — Coumarone indeneresin 3 (Tg: −30° C.) — — — — — — — — — α-Methyl styrene resin (Tg: 95°C.) — — — — — — — — — Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5Stearic acid 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 Wax 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 Vulcanizationaccelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing andkneading processability index 101 102 105 101 107 108 104 100 98Low-heat-build-property index 131 128 129 128 124 125 115 100 95 tan δpeak temperature −14 −14 −14 −14 −14 −14 −14 −14 −16 Rubber strengthindex 108 107 106 108 109 106 110 100 107 Abrasion resistance index 110107 111 110 108 109 111 100 96 Wet-grip performance index 108 108 107109 110 108 108 100 97 Handling stability 6 6 6 6 6 6 6 6 5.75Comparative Example Example 44 45 49 52 185 186 187 FormulationCopolymer (8) — — 60 — 60 60 60 (parts by Copolymer (12) — — — — — — —mass) Copolymer (14) 60 — — — — — — Copolymer (15) — 60 — — — — —Copolymer (19) — — 20 — — — — Copolymer (22) — — — — — — — Copolymer(23) — — — — — — — Copolymer (24) — — — — — — — Copolymer (25) — — — — —— — Copolymer (26) — — — — — — — Copolymer (27) — — — — 20 — — Copolymer(28) — — — — — — — Copolymer (29) — — — — — — — Copolymer (30) — — — 60— — — Copolymer (31) — — — — — 20 — Copolymer (32) — — — — — — 20Natural rubber 20 20 20 20 20 20 20 Polybutadiene rubber 20 20 — 20 — —— Silica 2 (N₂SA: 110 m²/g) 75 75 75 75 75 75 75 Silane coupling agent A6 6 6 6 6 6 6 Carbon black 15 15 15 15 15 15 15 Oil 25 25 25 25 25 25 25Coumarone indene resin 1 (Tg: 90° C.) 10 10 10 10 10 10 10 Coumaroneindene resin 2 (Tg: 10° C.) — — — — — — — Coumarone indene resin 3 (Tg:−30° C.) — — — — — — — α-Methyl styrene resin (Tg: 95° C.) — — — — — — —Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 Zincoxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing and kneadingprocessability index 97 95 99 98 102 103 101 Low-heat-build-propertyindex 101 100 109 100 109 112 107 tan δ peak temperature −14 −14 −13 −14−14 −14 −14 Rubber strength index 102 101 98 103 105 106 105 Abrasionresistance index 92 91 101 102 108 109 111 Wet-grip performance index 9899 106 105 111 109 107 Handling stability 6 6 5.5 5.5 6 6 6

TABLE 22 Examples in which a compound represented by the formula (IIId)is used as a Terminal modifier Comparative Example Example Com. Ex. Ex.Com. Ex. 40 43 173 188 189 190 191 53 192 54 Formulation Copolymer (7) —— 60 60 60 60 60 30 70 100 (parts by Copolymer (8) 60 — — — — — — — — —mass) Copolymer (12) — 60 — — — — — — — — Natural rubber 20 20 20 20 2020 20 50 10 — Polybutadiene rubber 20 20 20 20 20 20 20 20 20 — Silica 2(N₂SA: 110 m²/g) 75 75 75 75 75 75 75 75 75 75 Silane coupling agent A 66 6 6 6 6 6 6 6 6 Carbon black 15 15 15 15 15 15 15 15 15 15 Oil 25 2525 25 25 25 25 25 25 25 Coumarone indene resin 1 (Tg: 90° C.) 10 10 10 —20 10 10 10 10 10 Coumarone indene resin 2 (Tg: 10° C.) — — — — — 5 — —— — Coumarone indene resin 3 (Tg: −30° C.) — — — — — — 5 — — — α-Methylstyrene resin (Tg: 95° C.) — — — 10 — — — — — — Antioxidant 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 2 2 2 2 2 2 2 2 2 2 Zinc oxide2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 Sulfur 22 2 2 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.81.8 1.8 1.8 1.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 1.2 Evaluation Mixing and kneading processability index 100 98103 103 115 109 111 124 107 80 Low-heat-build-property index 100 95 139138 134 136 139 130 140 128 tan δ peak temperature −14 −16 −14 −14 −14−15 −16 −20 −13 −11 Rubber strength index 100 107 102 102 108 106 107132 101 85 Abrasion resistance index 100 96 103 99 101 101 104 114 10792 Wet-grip performance index 100 97 113 116 123 114 116 92 114 127Handling stability 6 5.75 6.25 6.25 6 6 6 5.5 6.5 5.5

TABLE 23 Examples in which a compound represented by the formula (IIIb)is used as a Terminal modifier Example 193 194 195 196 197 198 199 200201 Formulation Copolymer (8) — — — — — — — — — (parts by Copolymer (12)— — — — — — — — — mass) Copolymer (14) — — — — — — — — — Copolymer (15)— — — — — — — — — Copolymer (19) — — — — — — — — — Copolymer (33) 60 — —— — — — — — Copolymer (34) — 60 — — — — — — — Copolymer (35) — — 60 — —— — — — Copolymer (36) — — — 60 — — — — — Copolymer (37) — — — — 60 — —— — Copolymer (38) — — — — — 60 — — — Copolymer (39) — — — — — — 60 — —Copolymer (40) — — — — — — — 60 — Copolymer (41) — — — — — — — — 60Copolymer (42) — — — — — — — — — Natural rubber 20 20 20 20 20 20 20 2020 Polybutadiene rubber 20 20 20 20 20 20 20 20 20 Silica 2 (N₂SA: 110m²/g) 75 75 75 75 75 75 75 75 75 Silane coupling agent A 6 6 6 6 6 6 6 66 Carbon black 15 15 15 15 15 15 15 15 15 Oil 25 25 25 25 25 25 25 25 25Coumarone indene resin 1 (Tg: 90° C.) 10 10 10 10 10 10 10 10 10Coumarone indene resin 2 (Tg: 10° C.) — — — — — — — — — Coumarone indeneresin 3 (Tg: −30° C.) — — — — — — — — — α-Methyl styrene resin (Tg: 95°C.) — — — — — — — — — Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5Stearic acid 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 Wax 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 Vulcanizationaccelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Vulcanizationaccelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Evaluation Mixing andkneading processability index 104 109 105 104 105 109 104 105 103Low-heat-build-property index 121 117 118 111 121 108 118 105 103 tan δpeak temperature −15 −15 −15 −15 −15 −15 −15 −15 −15 Rubber strengthindex 109 110 109 111 108 111 109 113 111 Abrasion resistance index 102102 101 104 102 103 101 104 103 Wet-grip performance index 103 103 102112 102 111 105 108 107 Handling stability 6.25 6 6 6 6.25 6.25 6 6 6Comparative Example 40 43 44 45 49 55 Formulation Copolymer (8) 60 — — —60 — (parts by Copolymer (12) — 60 — — — — mass) Copolymer (14) — — 60 —— — Copolymer (15) — — — 60 — — Copolymer (19) — — — — 20 — Copolymer(33) — — — — — — Copolymer (34) — — — — — — Copolymer (35) — — — — — —Copolymer (36) — — — — — — Copolymer (37) — — — — — — Copolymer (38) — —— — — — Copolymer (39) — — — — — — Copolymer (40) — — — — — — Copolymer(41) — — — — — — Copolymer (42) — — — — — 60 Natural rubber 20 20 20 2020 20 Polybutadiene rubber 20 20 20 20 — 20 Silica 2 (N₂SA: 110 m²/g) 7575 75 75 75 75 Silane coupling agent A 6 6 6 6 6 6 Carbon black 15 15 1515 15 15 Oil 25 25 25 25 25 25 Coumarone indene resin 1 (Tg: 90° C.) 1010 10 10 10 10 Coumarone indene resin 2 (Tg: 10° C.) — — — — — —Coumarone indene resin 3 (Tg: −30° C.) — — — — — — α-Methyl styreneresin (Tg: 95° C.) — — — — — — Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5Stearic acid 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 Wax 1 1 1 11 1 Sulfur 2 2 2 2 2 2 Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.81.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 EvaluationMixing and kneading processability index 100 98 97 95 99 96Low-heat-build-property index 100 95 101 100 109 97 tan δ peaktemperature −14 −16 −14 −14 −13 −15 Rubber strength index 100 107 102101 98 108 Abrasion resistance index 100 96 92 91 101 93 Wet-gripperformance index 100 97 98 99 106 102 Handling stability 6 5.75 6 6 5.56

TABLE 24 Examples in which a compound containing an alkoxysilyl group, anitrogen atom and a carbonyl group is used as a Terminal modifierExample Comparative Example 202 203 204 205 206 207 40 43 44 45 49 56Formulation Copolymer (8) — — — — — — 60 — — — 60 — (parts by Copolymer(12) — — — — — — — 60 — — — — mass) Copolymer (14) — — — — — — — — 60 —— — Copolymer (15) — — — — — — — — — 60 — — Copolymer (19) — — — — — — —— — — 20 — Copolymer (43) 60 — — — — — — — — — — — Copolymer (44) — 60 —— — _(—) — — — — — — Copolymer (45) — — 60 — — — — — — — — — Copolymer(46) — — — 60 — — — — — — — — Copolymer (47) — — — — 60 — — — — — — —Copolymer (48) — — — — — 60 — — — — — — Copolymer (49) — — — — — — — — —— — 60 Natural rubber 20 20 20 20 20 20 20 20 20 20 20 20 Polybutadienerubber 20 20 20 20 20 20 20 20 20 20 — 20 Silica 2 (N₂SA: 110 m²/g) 7575 75 75 75 75 75 75 75 75 75 75 Silane coupling agent A 6 6 6 6 6 6 6 66 6 6 6 Carbon black 15 15 15 15 15 15 15 15 15 15 15 15 Oil 25 25 25 2525 25 25 25 25 25 25 25 Coumarone indene resin 1 10 10 10 10 10 10 10 1010 10 10 10 (Tg: 90° C.) Coumarone indene resin 2 — — — — — — — — — — —— (Tg: 10° C.) Coumarone indene resin 3 — — — — — — — — — — — — (Tg:−30° C.) α-Methyl styrene resin — — — — — — — — — — — — (Tg: 95° C.)Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid2 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 Evaluation Mixing and kneading 108 107 105 104 102 107 100 98 9795 99 98 processability index Low-heat-build-property 116 108 115 112116 107 100 95 101 100 109 94 index tan δ peak temperature −15 −15 −15−15 −15 −15 −14 −16 −14 −14 −13 −15 Rubber strength index 106 108 106107 106 109 100 107 102 101 98 107 Abrasion resistance index 107 106 102103 104 103 100 96 92 91 101 92 Wet-grip performance index 102 108 106109 110 110 100 97 98 99 106 100 Handling stability 6 6 6 6 6 6 6 5.75 66 5.5 6

TABLE 25 Examples in which an N,N-dialkyl-substituted carboxylic acidamide dialkyl acetal compound is used as a Terminal modifier ExampleComparative Example 208 209 210 211 212 213 40 43 44 45 49 57Formulation Copolymer (8) — — — — — — 60 — — — 60 — (parts by Copolymer(12) — — — — — — — 60 — — — — mass) Copolymer (14) — — — — — — — — 60 —— — Copolymer (15) — — — — — — — — — 60 — — Copolymer (19) — — — — — — —— — — 20 — Copolymer (50) 60 — — — — — — — — — — — Copolymer (51) — 60 —— — — — — — — — — Copolymer (52) — — 60 — — — — — — — — — Copolymer (53)— — — 60 — — — — — — — — Copolymer (54) — — — — 60 — — — — — — —Copolymer (55) — — — — — 60 — — — — — — Copolymer (56) — — — — — — — — —— — 60 Natural rubber 20 20 20 20 20 20 20 20 20 20 20 20 Polybutadienerubber 20 20 20 20 20 20 20 20 20 20 — 20 Silica 2 (N₂SA: 110 m²/g) 7575 75 75 75 75 75 75 75 75 75 75 Silane coupling agent A 6 6 6 6 6 6 6 66 6 6 6 Carbon black 15 15 15 15 15 15 15 15 15 15 15 15 Oil 25 25 25 2525 25 25 25 25 25 25 25 Coumarone indene resin 1 10 10 10 10 10 10 10 1010 10 10 10 (Tg: 90° C.) Coumarone indene resin 2 — — — — — — — — — — —— (Tg: 10° C.) Coumarone indene resin 3 — — — — — — — — — — — — (Tg:−30° C.) α-Methyl styrene resin — — — — — — — — — — — — (Tg: 95° C.)Antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid2 2 2 2 2 2 2 2 2 2 2 2 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 2.5 2.5 Wax 1 1 1 1 1 1 1 1 1 1 1 1 Sulfur 2 2 2 2 2 2 2 2 2 2 2 2Vulcanization accelerator 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.81.8 Vulcanization accelerator 2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.21.2 1.2 Evaluation Mixing and kneading 105 107 106 106 102 108 100 98 9795 99 96 processability index Low-heat-build-property 117 110 108 114113 106 100 95 101 100 109 94 index tan δ peak temperature −15 −15 −15−15 −15 −15 −14 −16 −14 −14 −13 −15 Rubber strength index 107 108 106106 107 109 100 107 102 101 98 107 Abrasion resistance index 108 107 103102 103 102 100 96 92 91 101 91 Wet-grip performance index 101 106 110107 112 109 100 97 98 99 106 100 Handling stability 6 6 6 6 6 6 6 5.75 66 5.5 6

As shown in Tables 6 to 25, since each of the rubber compositions of theexamples contains a specific amount or more of SBR as well as a specificamount of a silica and a specific amount of a conjugated diene copolymerhaving a specific amine structure at an initiation terminal, astructural unit derived from a silicon-containing compound at a mainchain, and a structural unit derived from a compound containing anitrogen atom and/or a silicon atom at a termination terminal, theserubber compositions exhibited a balanced improvement in processability,fuel economy, rubber strength, abrasion resistance, wet-gripperformance, and handling stability as compared to the rubbercompositions of the comparative examples. Moreover, comparison betweenthe conjugated diene polymer in which the three sites (the initiationterminal, main chain, and termination terminal) are modified by specificcompounds, and a copolymer in which only one of the initiation terminal,main chain, and termination terminal is modified shows that modificationof the three sites (the initiation terminal, main chain, and terminationterminal) synergistically increases the effects of improving thoseproperties.

The rubber compositions of Examples 21 to 35 and 37 to 213, eachcontaining the conjugated diene polymer together with at least one of amercapto group-containing silane coupling agent, a combination of twokinds of silica having specific nitrogen adsorption specific surfaceareas, and a solid resin having a specific glass transition temperature,exhibited greatly improved properties.

Each of the rubber compositions of Comparative Example 8, 29, and 47contains, instead of the conjugated diene polymer, the copolymer (17)which has a structural unit derived from a silicon-containing compoundat a main chain and a structural unit derived from a compound containinga nitrogen atom and/or a silicon atom at a termination terminal but doesnot have a specific amine structure at an initiation terminal. Therubber compositions of Comparative Examples 8, 29, and 47 have inferiorproperties to those in the examples, and furthermore, have poor abrasionresistance and processability as compared to those of the standardcomparative examples.

The rubber composition of Comparative Example 53 containing theconjugated rubber composition and a small amount of SBR was inferior inwet-grip performance and handling stability to the rubber composition ofComparative Example 1.

Each of the rubber compositions of Comparative Examples 15, 36, and 54contains too large an amount of the conjugated diene polymer. Thus, theabrasion resistance and other properties were very poor.

The invention claimed is:
 1. A rubber composition, comprising, based on 100% by mass of a rubber component, not less than 35% by mass of styrene-butadiene rubber, the rubber composition comprising a conjugated diene polymer, and a silica having a nitrogen adsorption specific surface area of 40 to 400 m²/g, the conjugated diene polymer being obtained by polymerizing a monomer component including a conjugated diene compound and a silicon-containing vinyl compound in the presence of a polymerization initiator represented by the following formula (I):

wherein i represents 0 or 1; R¹¹ represents a C₇₋₈₀ hydrocarbylene group; R¹² and R¹³ each are a hydrocarbyl group, or R12 and R13 are joined together to form a hydrocarbylene group; and M represents an alkali metal atom, to produce a copolymer, and then reacting a compound containing at least one of a nitrogen atom and a silicon atom with an active terminal of the copolymer, wherein the silicon-containing vinyl compound is a compound represented by the following formula (II):

wherein m represents 0; X¹, X² and X³ each represent a group represented by the following formula (IIa), or a hydrocarbyl group; at least one of X¹, X² and X³ is a group represented by the following formula (IIa),

wherein R²² and R²³ each are an alkyl group, wherein the compound containing at least one of a nitrogen atom and a silicon atom is at least one selected from the group consisting of a compound represented by the following formula (IIIb), a compound represented by the following formula (IIId), a compound represented by the following formula (IV), a tris[(alkoxysilyl)alkyl] isocyanurate compound, and an N,N-dialkyl-substituted carboxylic acid amide dialkyl acetal compound,

wherein R³² represents a hydrocarbyl group; and R³⁶ represents a hydrocarbylene group, or a group in which a hydrocarbylene group and a group represented by —NR³⁵— are bonded, where R³⁵ represents a hydrocarbyl group or a hydrogen atom,

where in R³¹ and R³² each represents a hydrocarbyl group; R³⁷ represents a hydrocarbylene group; A represents an oxygen atom or —NR³⁵— wherein R³⁵ represents a hydrocarbyl group or a hydrogen atom; and R³⁴ represents a hydrocarbyl group or a hydrogen atom,

wherein R⁴¹ represents a hydrocarbyl group; R⁴² and R⁴³ each represent a hydrocarbyl group or a hydrocarbyloxy group; R⁴⁴ and R⁴⁵ each represents a hydro carbyl group; and j represents an integer of 1 to 5, wherein an amount of the conjugated diene polymer is 25 to 75% by mass and an amount of a polyisoprene-based rubber is 0 to 40% by mass, each based on 100% by mass of the rubber component, and an amount of the silica is 10 to 150 parts by mass for each 100 parts by mass of the rubber component.
 2. The rubber composition according to claim 1, wherein R¹¹ in the formula (I) is a group represented by the following formula (Ia):

wherein R¹⁴ represents a hydrocarbylene group comprising at least one of a structural unit derived from a conjugated diene compound and a structural unit derived from an aromatic vinyl compound; and n represents an integer of 1 to
 10. 3. The rubber composition according to claim 2, wherein R¹⁴ in the formula (Ia) is a hydrocarbylene group comprising from one to ten isoprene-derived structural unit(s).
 4. The rubber composition according to claim 1, wherein the conjugated diene polymer contains a structural unit derived from an aromatic vinyl compound.
 5. The rubber composition according to claim 1, wherein the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 50 m²/g but less than 120 m²/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m²/g.
 6. The rubber composition according to claim 1, comprising a solid resin having a glass transition temperature of 60 to 120° C. in an amount of 1 to 30 parts by mass for each 100 parts by mass of the rubber component.
 7. The rubber composition according to claim 1, wherein the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 50 m²/g but less than 120 m²/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m²/g, and the rubber composition comprises a solid resin having a glass transition temperature of 60 to 120° C. in an amount of 1 to 30 parts by mass for each 100 parts by mass of the rubber component.
 8. The rubber composition according to claim 1, comprising a mercapto group-containing silane coupling agent in an amount of 0.5 to 20 parts by mass for each 100 parts by mass of the silica.
 9. The rubber composition according to claim 1, wherein the rubber composition comprises a mercapto group-containing silane coupling agent in an amount of 0.5 to 20 parts by mass for each 100 parts by mass of the silica, and the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 50 m²/g but less than 120 m²/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m²/g.
 10. The rubber composition according to claim 1, comprising a mercapto group-containing silane coupling agent in an amount of 0.5 to 20 parts by mass for each 100 parts by mass of the silica, and a solid resin having a glass transition temperature of 60 to 120° C. in an amount of 1 to 30 parts by mass for each 100 parts by mass of the rubber component.
 11. The rubber composition according to claim 1, wherein the rubber composition comprises a mercapto group-containing silane coupling agent in an amount of 0.5 to 20 parts by mass for each 100 parts by mass of the silica, the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 50 m²/g but less than 120 m²/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m²/g, and the rubber composition comprises a solid resin having a glass transition temperature of 60 to 120° C. in an amount of 1 to 30 parts by mass for each 100 parts by mass of the rubber component.
 12. The rubber composition according to claim 1, wherein the rubber composition comprises a mercapto group-containing silane coupling agent in an amount of 0.5 to 20 parts by mass for each 100 parts by mass of the silica, and the silane coupling agent is at least one of a compound represented by the formula (1) below, and a compound containing a linking unit A represented by the formula (2) below and a linking unit B represented by the formula (3) below,

wherein R¹⁰¹ to R¹⁰³ each represent a branched or unbranched C₁₋₁₂ alkyl group, a branched or unbranched C₁₋₁₂ alkoxy group, or a group represented by —O—(R¹¹¹—O)_(z)—R¹¹² where z R¹¹¹s each represent a branched or unbranched C₁-30 divalent hydrocarbon group, and z R¹¹¹s may be the same as or different from one another; R¹¹² represents a branched or unbranched C₁₋₃₀ alkyl group, a branched or unbranched C₂-30 alkenyl group, a C₆-30 aryl group, or a C₇-30 aralkyl group; and z represents an integer of 1 to 30, and R¹⁰¹ to R¹⁰³ may be the same as or different from one another; and R¹⁰⁴ represents a branched or unbranched C₁₋₆ alkylene group;

wherein R²⁰¹ represents a hydrogen atom, a halogen atom, a branched or unbranched C₁₋₃₀ alkyl group, a branched or unbranched C₂-30 alkenyl group, a branched or unbranched C₂₋₃₀ alkynyl group, or the alkyl group in which a terminal hydrogen atom is replaced with a hydroxyl group or a carboxyl group; R²⁰² represents a branched or unbranched C₁₋₃₀ alkylene group, a branched or unbranched C₂-30 alkenylene group, or a branched or unbranched C₂-30 alkynylene group; and R²⁰¹ and R²⁰² may be joined together to form a cyclic structure.
 13. The rubber composition according to claim 1, wherein the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 50 m²/g but less than 120 m²/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m²/g, and the nitrogen adsorption specific surface areas and amounts of the silica (1) and the silica (2) satisfy the following inequalities: (Nitrogen adsorption specific surface area of silica (2))/(Nitrogen adsorption specific surface area of silica (1))≧1.4, and (Amount of silica (1))×0.06≦(Amount of silica (2))≦(Amount of silica (1))×15.
 14. The rubber composition according to claim 1, comprising at least one of at least one liquid resin having a glass transition temperature of −40 to 20° C. selected from the group consisting of aromatic petroleum resins, terpene resins, and rosin resins, and a plasticizer having a glass transition temperature of −40 to 20° C., wherein a combined amount of the liquid resin and the plasticizer is 1 to 30 parts by mass for each 100 parts by mass of the rubber component.
 15. The rubber composition according to claim 1, wherein the rubber composition has a tan δ peak temperature of not lower than −16° C.
 16. A tread, formed from the rubber composition according to claim
 1. 17. A pneumatic tire, formed from the rubber composition according to claim
 1. 18. The pneumatic tire according to claim 17, wherein the wet grip performance index is equal to or between 106 and 125 and the handling stability is equal to or between 6 and 6.5. 